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Diffstat (limited to 'libs/hwui/PathTessellator.cpp')
| -rw-r--r-- | libs/hwui/PathTessellator.cpp | 970 |
1 files changed, 970 insertions, 0 deletions
diff --git a/libs/hwui/PathTessellator.cpp b/libs/hwui/PathTessellator.cpp new file mode 100644 index 000000000000..69ccdfa12ebd --- /dev/null +++ b/libs/hwui/PathTessellator.cpp @@ -0,0 +1,970 @@ +/* + * Copyright (C) 2012 The Android Open Source Project + * + * Licensed under the Apache License, Version 2.0 (the "License"); + * you may not use this file except in compliance with the License. + * You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, software + * distributed under the License is distributed on an "AS IS" BASIS, + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + * See the License for the specific language governing permissions and + * limitations under the License. + */ + +#define LOG_TAG "PathTessellator" +#define LOG_NDEBUG 1 +#define ATRACE_TAG ATRACE_TAG_GRAPHICS + +#define VERTEX_DEBUG 0 + +#if VERTEX_DEBUG +#define DEBUG_DUMP_ALPHA_BUFFER() \ + for (unsigned int i = 0; i < vertexBuffer.getSize(); i++) { \ + ALOGD("point %d at %f %f, alpha %f", \ + i, buffer[i].position[0], buffer[i].position[1], buffer[i].alpha); \ + } +#define DEBUG_DUMP_BUFFER() \ + for (unsigned int i = 0; i < vertexBuffer.getSize(); i++) { \ + ALOGD("point %d at %f %f", i, buffer[i].position[0], buffer[i].position[1]); \ + } +#else +#define DEBUG_DUMP_ALPHA_BUFFER() +#define DEBUG_DUMP_BUFFER() +#endif + +#include <SkPath.h> +#include <SkPaint.h> + +#include <stdlib.h> +#include <stdint.h> +#include <sys/types.h> + +#include <utils/Log.h> +#include <utils/Trace.h> + +#include "PathTessellator.h" +#include "Matrix.h" +#include "Vector.h" +#include "Vertex.h" + +namespace android { +namespace uirenderer { + +#define THRESHOLD 0.5f +#define ROUND_CAP_THRESH 0.25f +#define PI 3.1415926535897932f + +void PathTessellator::expandBoundsForStroke(SkRect& bounds, const SkPaint* paint, + bool forceExpand) { + if (forceExpand || paint->getStyle() != SkPaint::kFill_Style) { + float outset = paint->getStrokeWidth() * 0.5f; + bounds.outset(outset, outset); + } +} + +inline void copyVertex(Vertex* destPtr, const Vertex* srcPtr) { + Vertex::set(destPtr, srcPtr->position[0], srcPtr->position[1]); +} + +inline void copyAlphaVertex(AlphaVertex* destPtr, const AlphaVertex* srcPtr) { + AlphaVertex::set(destPtr, srcPtr->position[0], srcPtr->position[1], srcPtr->alpha); +} + +/** + * Produces a pseudo-normal for a vertex, given the normals of the two incoming lines. If the offset + * from each vertex in a perimeter is calculated, the resultant lines connecting the offset vertices + * will be offset by 1.0 + * + * Note that we can't add and normalize the two vectors, that would result in a rectangle having an + * offset of (sqrt(2)/2, sqrt(2)/2) at each corner, instead of (1, 1) + * + * NOTE: assumes angles between normals 90 degrees or less + */ +inline vec2 totalOffsetFromNormals(const vec2& normalA, const vec2& normalB) { + return (normalA + normalB) / (1 + fabs(normalA.dot(normalB))); +} + +/** + * Structure used for storing useful information about the SkPaint and scale used for tessellating + */ +struct PaintInfo { +public: + PaintInfo(const SkPaint* paint, const mat4 *transform) : + style(paint->getStyle()), cap(paint->getStrokeCap()), isAA(paint->isAntiAlias()), + inverseScaleX(1.0f), inverseScaleY(1.0f), + halfStrokeWidth(paint->getStrokeWidth() * 0.5f), maxAlpha(1.0f) { + // compute inverse scales + if (CC_UNLIKELY(!transform->isPureTranslate())) { + float m00 = transform->data[Matrix4::kScaleX]; + float m01 = transform->data[Matrix4::kSkewY]; + float m10 = transform->data[Matrix4::kSkewX]; + float m11 = transform->data[Matrix4::kScaleY]; + float scaleX = sqrt(m00 * m00 + m01 * m01); + float scaleY = sqrt(m10 * m10 + m11 * m11); + inverseScaleX = (scaleX != 0) ? (1.0f / scaleX) : 1.0f; + inverseScaleY = (scaleY != 0) ? (1.0f / scaleY) : 1.0f; + } + + if (isAA && halfStrokeWidth != 0 && inverseScaleX == inverseScaleY && + halfStrokeWidth * inverseScaleX < 0.5f) { + maxAlpha *= (2 * halfStrokeWidth) / inverseScaleX; + halfStrokeWidth = 0.0f; + } + } + + SkPaint::Style style; + SkPaint::Cap cap; + bool isAA; + float inverseScaleX; + float inverseScaleY; + float halfStrokeWidth; + float maxAlpha; + + inline void scaleOffsetForStrokeWidth(vec2& offset) const { + if (halfStrokeWidth == 0.0f) { + // hairline - compensate for scale + offset.x *= 0.5f * inverseScaleX; + offset.y *= 0.5f * inverseScaleY; + } else { + offset *= halfStrokeWidth; + } + } + + /** + * NOTE: the input will not always be a normal, especially for sharp edges - it should be the + * result of totalOffsetFromNormals (see documentation there) + */ + inline vec2 deriveAAOffset(const vec2& offset) const { + return vec2(offset.x * 0.5f * inverseScaleX, + offset.y * 0.5f * inverseScaleY); + } + + /** + * Returns the number of cap divisions beyond the minimum 2 (kButt_Cap/kSquareCap will return 0) + * Should only be used when stroking and drawing caps + */ + inline int capExtraDivisions() const { + if (cap == SkPaint::kRound_Cap) { + if (halfStrokeWidth == 0.0f) return 2; + + // ROUND_CAP_THRESH is the maximum error for polygonal approximation of the round cap + const float errConst = (-ROUND_CAP_THRESH / halfStrokeWidth + 1); + const float targetCosVal = 2 * errConst * errConst - 1; + int neededDivisions = (int)(ceilf(PI / acos(targetCosVal)/2)) * 2; + return neededDivisions; + } + return 0; + } +}; + +void getFillVerticesFromPerimeter(const Vector<Vertex>& perimeter, VertexBuffer& vertexBuffer) { + Vertex* buffer = vertexBuffer.alloc<Vertex>(perimeter.size()); + + int currentIndex = 0; + // zig zag between all previous points on the inside of the hull to create a + // triangle strip that fills the hull + int srcAindex = 0; + int srcBindex = perimeter.size() - 1; + while (srcAindex <= srcBindex) { + copyVertex(&buffer[currentIndex++], &perimeter[srcAindex]); + if (srcAindex == srcBindex) break; + copyVertex(&buffer[currentIndex++], &perimeter[srcBindex]); + srcAindex++; + srcBindex--; + } +} + +/* + * Fills a vertexBuffer with non-alpha vertices, zig-zagging at each perimeter point to create a + * tri-strip as wide as the stroke. + * + * Uses an additional 2 vertices at the end to wrap around, closing the tri-strip + * (for a total of perimeter.size() * 2 + 2 vertices) + */ +void getStrokeVerticesFromPerimeter(const PaintInfo& paintInfo, const Vector<Vertex>& perimeter, + VertexBuffer& vertexBuffer) { + Vertex* buffer = vertexBuffer.alloc<Vertex>(perimeter.size() * 2 + 2); + + int currentIndex = 0; + const Vertex* last = &(perimeter[perimeter.size() - 1]); + const Vertex* current = &(perimeter[0]); + vec2 lastNormal(current->position[1] - last->position[1], + last->position[0] - current->position[0]); + lastNormal.normalize(); + for (unsigned int i = 0; i < perimeter.size(); i++) { + const Vertex* next = &(perimeter[i + 1 >= perimeter.size() ? 0 : i + 1]); + vec2 nextNormal(next->position[1] - current->position[1], + current->position[0] - next->position[0]); + nextNormal.normalize(); + + vec2 totalOffset = totalOffsetFromNormals(lastNormal, nextNormal); + paintInfo.scaleOffsetForStrokeWidth(totalOffset); + + Vertex::set(&buffer[currentIndex++], + current->position[0] + totalOffset.x, + current->position[1] + totalOffset.y); + + Vertex::set(&buffer[currentIndex++], + current->position[0] - totalOffset.x, + current->position[1] - totalOffset.y); + + last = current; + current = next; + lastNormal = nextNormal; + } + + // wrap around to beginning + copyVertex(&buffer[currentIndex++], &buffer[0]); + copyVertex(&buffer[currentIndex++], &buffer[1]); + + DEBUG_DUMP_BUFFER(); +} + +/** + * Fills a vertexBuffer with non-alpha vertices similar to getStrokeVerticesFromPerimeter, except: + * + * 1 - Doesn't need to wrap around, since the input vertices are unclosed + * + * 2 - can zig-zag across 'extra' vertices at either end, to create round caps + */ +void getStrokeVerticesFromUnclosedVertices(const PaintInfo& paintInfo, + const Vector<Vertex>& vertices, VertexBuffer& vertexBuffer) { + const int extra = paintInfo.capExtraDivisions(); + const int allocSize = (vertices.size() + extra) * 2; + + Vertex* buffer = vertexBuffer.alloc<Vertex>(allocSize); + + if (extra > 0) { + // tessellate both round caps + const int last = vertices.size() - 1; + float beginTheta = atan2( + - (vertices[0].position[0] - vertices[1].position[0]), + vertices[0].position[1] - vertices[1].position[1]); + float endTheta = atan2( + - (vertices[last].position[0] - vertices[last - 1].position[0]), + vertices[last].position[1] - vertices[last - 1].position[1]); + + const float dTheta = PI / (extra + 1); + const float radialScale = 2.0f / (1 + cos(dTheta)); + + int capOffset; + for (int i = 0; i < extra; i++) { + if (i < extra / 2) { + capOffset = extra - 2 * i - 1; + } else { + capOffset = 2 * i - extra; + } + + beginTheta += dTheta; + vec2 beginRadialOffset(cos(beginTheta), sin(beginTheta)); + paintInfo.scaleOffsetForStrokeWidth(beginRadialOffset); + Vertex::set(&buffer[capOffset], + vertices[0].position[0] + beginRadialOffset.x, + vertices[0].position[1] + beginRadialOffset.y); + + endTheta += dTheta; + vec2 endRadialOffset(cos(endTheta), sin(endTheta)); + paintInfo.scaleOffsetForStrokeWidth(endRadialOffset); + Vertex::set(&buffer[allocSize - 1 - capOffset], + vertices[last].position[0] + endRadialOffset.x, + vertices[last].position[1] + endRadialOffset.y); + } + } + + int currentIndex = extra; + const Vertex* current = &(vertices[0]); + vec2 lastNormal; + for (unsigned int i = 0; i < vertices.size() - 1; i++) { + const Vertex* next = &(vertices[i + 1]); + vec2 nextNormal(next->position[1] - current->position[1], + current->position[0] - next->position[0]); + nextNormal.normalize(); + + vec2 totalOffset; + if (i == 0) { + totalOffset = nextNormal; + } else { + totalOffset = totalOffsetFromNormals(lastNormal, nextNormal); + } + paintInfo.scaleOffsetForStrokeWidth(totalOffset); + + Vertex::set(&buffer[currentIndex++], + current->position[0] + totalOffset.x, + current->position[1] + totalOffset.y); + + Vertex::set(&buffer[currentIndex++], + current->position[0] - totalOffset.x, + current->position[1] - totalOffset.y); + + current = next; + lastNormal = nextNormal; + } + + vec2 totalOffset = lastNormal; + paintInfo.scaleOffsetForStrokeWidth(totalOffset); + + Vertex::set(&buffer[currentIndex++], + current->position[0] + totalOffset.x, + current->position[1] + totalOffset.y); + Vertex::set(&buffer[currentIndex++], + current->position[0] - totalOffset.x, + current->position[1] - totalOffset.y); + + DEBUG_DUMP_BUFFER(); +} + +/** + * Populates a vertexBuffer with AlphaVertices to create an anti-aliased fill shape tessellation + * + * 1 - create the AA perimeter of unit width, by zig-zagging at each point around the perimeter of + * the shape (using 2 * perimeter.size() vertices) + * + * 2 - wrap around to the beginning to complete the perimeter (2 vertices) + * + * 3 - zig zag back and forth inside the shape to fill it (using perimeter.size() vertices) + */ +void getFillVerticesFromPerimeterAA(const PaintInfo& paintInfo, const Vector<Vertex>& perimeter, + VertexBuffer& vertexBuffer) { + AlphaVertex* buffer = vertexBuffer.alloc<AlphaVertex>(perimeter.size() * 3 + 2); + + // generate alpha points - fill Alpha vertex gaps in between each point with + // alpha 0 vertex, offset by a scaled normal. + int currentIndex = 0; + const Vertex* last = &(perimeter[perimeter.size() - 1]); + const Vertex* current = &(perimeter[0]); + vec2 lastNormal(current->position[1] - last->position[1], + last->position[0] - current->position[0]); + lastNormal.normalize(); + for (unsigned int i = 0; i < perimeter.size(); i++) { + const Vertex* next = &(perimeter[i + 1 >= perimeter.size() ? 0 : i + 1]); + vec2 nextNormal(next->position[1] - current->position[1], + current->position[0] - next->position[0]); + nextNormal.normalize(); + + // AA point offset from original point is that point's normal, such that each side is offset + // by .5 pixels + vec2 totalOffset = paintInfo.deriveAAOffset(totalOffsetFromNormals(lastNormal, nextNormal)); + + AlphaVertex::set(&buffer[currentIndex++], + current->position[0] + totalOffset.x, + current->position[1] + totalOffset.y, + 0.0f); + AlphaVertex::set(&buffer[currentIndex++], + current->position[0] - totalOffset.x, + current->position[1] - totalOffset.y, + 1.0f); + + last = current; + current = next; + lastNormal = nextNormal; + } + + // wrap around to beginning + copyAlphaVertex(&buffer[currentIndex++], &buffer[0]); + copyAlphaVertex(&buffer[currentIndex++], &buffer[1]); + + // zig zag between all previous points on the inside of the hull to create a + // triangle strip that fills the hull, repeating the first inner point to + // create degenerate tris to start inside path + int srcAindex = 0; + int srcBindex = perimeter.size() - 1; + while (srcAindex <= srcBindex) { + copyAlphaVertex(&buffer[currentIndex++], &buffer[srcAindex * 2 + 1]); + if (srcAindex == srcBindex) break; + copyAlphaVertex(&buffer[currentIndex++], &buffer[srcBindex * 2 + 1]); + srcAindex++; + srcBindex--; + } + + DEBUG_DUMP_BUFFER(); +} + +/** + * Stores geometry for a single, AA-perimeter (potentially rounded) cap + * + * For explanation of constants and general methodoloyg, see comments for + * getStrokeVerticesFromUnclosedVerticesAA() below. + */ +inline void storeCapAA(const PaintInfo& paintInfo, const Vector<Vertex>& vertices, + AlphaVertex* buffer, bool isFirst, vec2 normal, int offset) { + const int extra = paintInfo.capExtraDivisions(); + const int extraOffset = (extra + 1) / 2; + const int capIndex = isFirst + ? 2 * offset + 6 + 2 * (extra + extraOffset) + : offset + 2 + 2 * extraOffset; + if (isFirst) normal *= -1; + + // TODO: this normal should be scaled by radialScale if extra != 0, see totalOffsetFromNormals() + vec2 AAOffset = paintInfo.deriveAAOffset(normal); + + vec2 strokeOffset = normal; + paintInfo.scaleOffsetForStrokeWidth(strokeOffset); + vec2 outerOffset = strokeOffset + AAOffset; + vec2 innerOffset = strokeOffset - AAOffset; + + vec2 capAAOffset; + if (paintInfo.cap != SkPaint::kRound_Cap) { + // if the cap is square or butt, the inside primary cap vertices will be inset in two + // directions - both normal to the stroke, and parallel to it. + capAAOffset = vec2(-AAOffset.y, AAOffset.x); + } + + // determine referencePoint, the center point for the 4 primary cap vertices + const Vertex* point = isFirst ? vertices.begin() : (vertices.end() - 1); + vec2 referencePoint(point->position[0], point->position[1]); + if (paintInfo.cap == SkPaint::kSquare_Cap) { + // To account for square cap, move the primary cap vertices (that create the AA edge) by the + // stroke offset vector (rotated to be parallel to the stroke) + referencePoint += vec2(-strokeOffset.y, strokeOffset.x); + } + + AlphaVertex::set(&buffer[capIndex + 0], + referencePoint.x + outerOffset.x + capAAOffset.x, + referencePoint.y + outerOffset.y + capAAOffset.y, + 0.0f); + AlphaVertex::set(&buffer[capIndex + 1], + referencePoint.x + innerOffset.x - capAAOffset.x, + referencePoint.y + innerOffset.y - capAAOffset.y, + paintInfo.maxAlpha); + + bool isRound = paintInfo.cap == SkPaint::kRound_Cap; + + const int postCapIndex = (isRound && isFirst) ? (2 * extraOffset - 2) : capIndex + (2 * extra); + AlphaVertex::set(&buffer[postCapIndex + 2], + referencePoint.x - outerOffset.x + capAAOffset.x, + referencePoint.y - outerOffset.y + capAAOffset.y, + 0.0f); + AlphaVertex::set(&buffer[postCapIndex + 3], + referencePoint.x - innerOffset.x - capAAOffset.x, + referencePoint.y - innerOffset.y - capAAOffset.y, + paintInfo.maxAlpha); + + if (isRound) { + const float dTheta = PI / (extra + 1); + const float radialScale = 2.0f / (1 + cos(dTheta)); + float theta = atan2(normal.y, normal.x); + int capPerimIndex = capIndex + 2; + + for (int i = 0; i < extra; i++) { + theta += dTheta; + + vec2 radialOffset(cos(theta), sin(theta)); + + // scale to compensate for pinching at sharp angles, see totalOffsetFromNormals() + radialOffset *= radialScale; + + AAOffset = paintInfo.deriveAAOffset(radialOffset); + paintInfo.scaleOffsetForStrokeWidth(radialOffset); + AlphaVertex::set(&buffer[capPerimIndex++], + referencePoint.x + radialOffset.x + AAOffset.x, + referencePoint.y + radialOffset.y + AAOffset.y, + 0.0f); + AlphaVertex::set(&buffer[capPerimIndex++], + referencePoint.x + radialOffset.x - AAOffset.x, + referencePoint.y + radialOffset.y - AAOffset.y, + paintInfo.maxAlpha); + + if (isFirst && i == extra - extraOffset) { + //copy most recent two points to first two points + copyAlphaVertex(&buffer[0], &buffer[capPerimIndex - 2]); + copyAlphaVertex(&buffer[1], &buffer[capPerimIndex - 1]); + + capPerimIndex = 2; // start writing the rest of the round cap at index 2 + } + } + + if (isFirst) { + const int startCapFillIndex = capIndex + 2 * (extra - extraOffset) + 4; + int capFillIndex = startCapFillIndex; + for (int i = 0; i < extra + 2; i += 2) { + copyAlphaVertex(&buffer[capFillIndex++], &buffer[1 + i]); + // TODO: to support odd numbers of divisions, break here on the last iteration + copyAlphaVertex(&buffer[capFillIndex++], &buffer[startCapFillIndex - 3 - i]); + } + } else { + int capFillIndex = 6 * vertices.size() + 2 + 6 * extra - (extra + 2); + for (int i = 0; i < extra + 2; i += 2) { + copyAlphaVertex(&buffer[capFillIndex++], &buffer[capIndex + 1 + i]); + // TODO: to support odd numbers of divisions, break here on the last iteration + copyAlphaVertex(&buffer[capFillIndex++], &buffer[capIndex + 3 + 2 * extra - i]); + } + } + return; + } + if (isFirst) { + copyAlphaVertex(&buffer[0], &buffer[postCapIndex + 2]); + copyAlphaVertex(&buffer[1], &buffer[postCapIndex + 3]); + copyAlphaVertex(&buffer[postCapIndex + 4], &buffer[1]); // degenerate tris (the only two!) + copyAlphaVertex(&buffer[postCapIndex + 5], &buffer[postCapIndex + 1]); + } else { + copyAlphaVertex(&buffer[6 * vertices.size()], &buffer[postCapIndex + 1]); + copyAlphaVertex(&buffer[6 * vertices.size() + 1], &buffer[postCapIndex + 3]); + } +} + +/* +the geometry for an aa, capped stroke consists of the following: + + # vertices | function +---------------------------------------------------------------------- +a) 2 | Start AA perimeter +b) 2, 2 * roundDivOff | First half of begin cap's perimeter + | + 2 * middlePts | 'Outer' or 'Top' AA perimeter half (between caps) + | +a) 4 | End cap's +b) 2, 2 * roundDivs, 2 | AA perimeter + | + 2 * middlePts | 'Inner' or 'bottom' AA perimeter half + | +a) 6 | Begin cap's perimeter +b) 2, 2*(rD - rDO + 1), | Last half of begin cap's perimeter + roundDivs, 2 | + | + 2 * middlePts | Stroke's full opacity center strip + | +a) 2 | end stroke +b) 2, roundDivs | (and end cap fill, for round) + +Notes: +* rows starting with 'a)' denote the Butt or Square cap vertex use, 'b)' denote Round + +* 'middlePts' is (number of points in the unclosed input vertex list, minus 2) times two + +* 'roundDivs' or 'rD' is the number of extra vertices (beyond the minimum of 2) that define the + round cap's shape, and is at least two. This will increase with cap size to sufficiently + define the cap's level of tessellation. + +* 'roundDivOffset' or 'rDO' is the point about halfway along the start cap's round perimeter, where + the stream of vertices for the AA perimeter starts. By starting and ending the perimeter at + this offset, the fill of the stroke is drawn from this point with minimal extra vertices. + +This means the outer perimeter starts at: + outerIndex = (2) OR (2 + 2 * roundDivOff) +the inner perimeter (since it is filled in reverse) starts at: + innerIndex = outerIndex + (4 * middlePts) + ((4) OR (4 + 2 * roundDivs)) - 1 +the stroke starts at: + strokeIndex = innerIndex + 1 + ((6) OR (6 + 3 * roundDivs - 2 * roundDivOffset)) + +The total needed allocated space is either: + 2 + 4 + 6 + 2 + 3 * (2 * middlePts) = 14 + 6 * middlePts = 2 + 6 * pts +or, for rounded caps: + (2 + 2 * rDO) + (4 + 2 * rD) + (2 * (rD - rDO + 1) + + roundDivs + 4) + (2 + roundDivs) + 3 * (2 * middlePts) + = 14 + 6 * middlePts + 6 * roundDivs + = 2 + 6 * pts + 6 * roundDivs + */ +void getStrokeVerticesFromUnclosedVerticesAA(const PaintInfo& paintInfo, + const Vector<Vertex>& vertices, VertexBuffer& vertexBuffer) { + + const int extra = paintInfo.capExtraDivisions(); + const int allocSize = 6 * vertices.size() + 2 + 6 * extra; + + AlphaVertex* buffer = vertexBuffer.alloc<AlphaVertex>(allocSize); + + const int extraOffset = (extra + 1) / 2; + int offset = 2 * (vertices.size() - 2); + // there is no outer/inner here, using them for consistency with below approach + int currentAAOuterIndex = 2 + 2 * extraOffset; + int currentAAInnerIndex = currentAAOuterIndex + (2 * offset) + 3 + (2 * extra); + int currentStrokeIndex = currentAAInnerIndex + 7 + (3 * extra - 2 * extraOffset); + + const Vertex* last = &(vertices[0]); + const Vertex* current = &(vertices[1]); + vec2 lastNormal(current->position[1] - last->position[1], + last->position[0] - current->position[0]); + lastNormal.normalize(); + + // TODO: use normal from bezier traversal for cap, instead of from vertices + storeCapAA(paintInfo, vertices, buffer, true, lastNormal, offset); + + for (unsigned int i = 1; i < vertices.size() - 1; i++) { + const Vertex* next = &(vertices[i + 1]); + vec2 nextNormal(next->position[1] - current->position[1], + current->position[0] - next->position[0]); + nextNormal.normalize(); + + vec2 totalOffset = totalOffsetFromNormals(lastNormal, nextNormal); + vec2 AAOffset = paintInfo.deriveAAOffset(totalOffset); + + vec2 innerOffset = totalOffset; + paintInfo.scaleOffsetForStrokeWidth(innerOffset); + vec2 outerOffset = innerOffset + AAOffset; + innerOffset -= AAOffset; + + AlphaVertex::set(&buffer[currentAAOuterIndex++], + current->position[0] + outerOffset.x, + current->position[1] + outerOffset.y, + 0.0f); + AlphaVertex::set(&buffer[currentAAOuterIndex++], + current->position[0] + innerOffset.x, + current->position[1] + innerOffset.y, + paintInfo.maxAlpha); + + AlphaVertex::set(&buffer[currentStrokeIndex++], + current->position[0] + innerOffset.x, + current->position[1] + innerOffset.y, + paintInfo.maxAlpha); + AlphaVertex::set(&buffer[currentStrokeIndex++], + current->position[0] - innerOffset.x, + current->position[1] - innerOffset.y, + paintInfo.maxAlpha); + + AlphaVertex::set(&buffer[currentAAInnerIndex--], + current->position[0] - innerOffset.x, + current->position[1] - innerOffset.y, + paintInfo.maxAlpha); + AlphaVertex::set(&buffer[currentAAInnerIndex--], + current->position[0] - outerOffset.x, + current->position[1] - outerOffset.y, + 0.0f); + + current = next; + lastNormal = nextNormal; + } + + // TODO: use normal from bezier traversal for cap, instead of from vertices + storeCapAA(paintInfo, vertices, buffer, false, lastNormal, offset); + + DEBUG_DUMP_ALPHA_BUFFER(); +} + + +void getStrokeVerticesFromPerimeterAA(const PaintInfo& paintInfo, const Vector<Vertex>& perimeter, + VertexBuffer& vertexBuffer) { + AlphaVertex* buffer = vertexBuffer.alloc<AlphaVertex>(6 * perimeter.size() + 8); + + int offset = 2 * perimeter.size() + 3; + int currentAAOuterIndex = 0; + int currentStrokeIndex = offset; + int currentAAInnerIndex = offset * 2; + + const Vertex* last = &(perimeter[perimeter.size() - 1]); + const Vertex* current = &(perimeter[0]); + vec2 lastNormal(current->position[1] - last->position[1], + last->position[0] - current->position[0]); + lastNormal.normalize(); + for (unsigned int i = 0; i < perimeter.size(); i++) { + const Vertex* next = &(perimeter[i + 1 >= perimeter.size() ? 0 : i + 1]); + vec2 nextNormal(next->position[1] - current->position[1], + current->position[0] - next->position[0]); + nextNormal.normalize(); + + vec2 totalOffset = totalOffsetFromNormals(lastNormal, nextNormal); + vec2 AAOffset = paintInfo.deriveAAOffset(totalOffset); + + vec2 innerOffset = totalOffset; + paintInfo.scaleOffsetForStrokeWidth(innerOffset); + vec2 outerOffset = innerOffset + AAOffset; + innerOffset -= AAOffset; + + AlphaVertex::set(&buffer[currentAAOuterIndex++], + current->position[0] + outerOffset.x, + current->position[1] + outerOffset.y, + 0.0f); + AlphaVertex::set(&buffer[currentAAOuterIndex++], + current->position[0] + innerOffset.x, + current->position[1] + innerOffset.y, + paintInfo.maxAlpha); + + AlphaVertex::set(&buffer[currentStrokeIndex++], + current->position[0] + innerOffset.x, + current->position[1] + innerOffset.y, + paintInfo.maxAlpha); + AlphaVertex::set(&buffer[currentStrokeIndex++], + current->position[0] - innerOffset.x, + current->position[1] - innerOffset.y, + paintInfo.maxAlpha); + + AlphaVertex::set(&buffer[currentAAInnerIndex++], + current->position[0] - innerOffset.x, + current->position[1] - innerOffset.y, + paintInfo.maxAlpha); + AlphaVertex::set(&buffer[currentAAInnerIndex++], + current->position[0] - outerOffset.x, + current->position[1] - outerOffset.y, + 0.0f); + + last = current; + current = next; + lastNormal = nextNormal; + } + + // wrap each strip around to beginning, creating degenerate tris to bridge strips + copyAlphaVertex(&buffer[currentAAOuterIndex++], &buffer[0]); + copyAlphaVertex(&buffer[currentAAOuterIndex++], &buffer[1]); + copyAlphaVertex(&buffer[currentAAOuterIndex++], &buffer[1]); + + copyAlphaVertex(&buffer[currentStrokeIndex++], &buffer[offset]); + copyAlphaVertex(&buffer[currentStrokeIndex++], &buffer[offset + 1]); + copyAlphaVertex(&buffer[currentStrokeIndex++], &buffer[offset + 1]); + + copyAlphaVertex(&buffer[currentAAInnerIndex++], &buffer[2 * offset]); + copyAlphaVertex(&buffer[currentAAInnerIndex++], &buffer[2 * offset + 1]); + // don't need to create last degenerate tri + + DEBUG_DUMP_ALPHA_BUFFER(); +} + +void PathTessellator::tessellatePath(const SkPath &path, const SkPaint* paint, + const mat4 *transform, VertexBuffer& vertexBuffer) { + ATRACE_CALL(); + + const PaintInfo paintInfo(paint, transform); + + Vector<Vertex> tempVertices; + float threshInvScaleX = paintInfo.inverseScaleX; + float threshInvScaleY = paintInfo.inverseScaleY; + if (paintInfo.style == SkPaint::kStroke_Style) { + // alter the bezier recursion threshold values we calculate in order to compensate for + // expansion done after the path vertices are found + SkRect bounds = path.getBounds(); + if (!bounds.isEmpty()) { + threshInvScaleX *= bounds.width() / (bounds.width() + paint->getStrokeWidth()); + threshInvScaleY *= bounds.height() / (bounds.height() + paint->getStrokeWidth()); + } + } + + // force close if we're filling the path, since fill path expects closed perimeter. + bool forceClose = paintInfo.style != SkPaint::kStroke_Style; + bool wasClosed = approximatePathOutlineVertices(path, forceClose, + threshInvScaleX * threshInvScaleX, threshInvScaleY * threshInvScaleY, tempVertices); + + if (!tempVertices.size()) { + // path was empty, return without allocating vertex buffer + return; + } + +#if VERTEX_DEBUG + for (unsigned int i = 0; i < tempVertices.size(); i++) { + ALOGD("orig path: point at %f %f", + tempVertices[i].position[0], tempVertices[i].position[1]); + } +#endif + + if (paintInfo.style == SkPaint::kStroke_Style) { + if (!paintInfo.isAA) { + if (wasClosed) { + getStrokeVerticesFromPerimeter(paintInfo, tempVertices, vertexBuffer); + } else { + getStrokeVerticesFromUnclosedVertices(paintInfo, tempVertices, vertexBuffer); + } + + } else { + if (wasClosed) { + getStrokeVerticesFromPerimeterAA(paintInfo, tempVertices, vertexBuffer); + } else { + getStrokeVerticesFromUnclosedVerticesAA(paintInfo, tempVertices, vertexBuffer); + } + } + } else { + // For kStrokeAndFill style, the path should be adjusted externally. + // It will be treated as a fill here. + if (!paintInfo.isAA) { + getFillVerticesFromPerimeter(tempVertices, vertexBuffer); + } else { + getFillVerticesFromPerimeterAA(paintInfo, tempVertices, vertexBuffer); + } + } +} + +static void expandRectToCoverVertex(SkRect& rect, const Vertex& vertex) { + rect.fLeft = fminf(rect.fLeft, vertex.position[0]); + rect.fTop = fminf(rect.fTop, vertex.position[1]); + rect.fRight = fmaxf(rect.fRight, vertex.position[0]); + rect.fBottom = fmaxf(rect.fBottom, vertex.position[1]); +} + +void PathTessellator::tessellateLines(const float* points, int count, SkPaint* paint, + const mat4* transform, SkRect& bounds, VertexBuffer& vertexBuffer) { + ATRACE_CALL(); + const PaintInfo paintInfo(paint, transform); + + const int extra = paintInfo.capExtraDivisions(); + int numLines = count / 4; + int lineAllocSize; + // pre-allocate space for lines in the buffer, and degenerate tris in between + if (paintInfo.isAA) { + lineAllocSize = 6 * (2) + 2 + 6 * extra; + vertexBuffer.alloc<AlphaVertex>(numLines * lineAllocSize + (numLines - 1) * 2); + } else { + lineAllocSize = 2 * ((2) + extra); + vertexBuffer.alloc<Vertex>(numLines * lineAllocSize + (numLines - 1) * 2); + } + + Vector<Vertex> tempVertices; + tempVertices.push(); + tempVertices.push(); + Vertex* tempVerticesData = tempVertices.editArray(); + bounds.set(points[0], points[1], points[0], points[1]); + for (int i = 0; i < count; i += 4) { + Vertex::set(&(tempVerticesData[0]), points[i + 0], points[i + 1]); + Vertex::set(&(tempVerticesData[1]), points[i + 2], points[i + 3]); + + if (paintInfo.isAA) { + getStrokeVerticesFromUnclosedVerticesAA(paintInfo, tempVertices, vertexBuffer); + } else { + getStrokeVerticesFromUnclosedVertices(paintInfo, tempVertices, vertexBuffer); + } + + // calculate bounds + expandRectToCoverVertex(bounds, tempVerticesData[0]); + expandRectToCoverVertex(bounds, tempVerticesData[1]); + } + + expandBoundsForStroke(bounds, paint, true); // force-expand bounds to incorporate stroke + + // since multiple objects tessellated into buffer, separate them with degen tris + if (paintInfo.isAA) { + vertexBuffer.createDegenerateSeparators<AlphaVertex>(lineAllocSize); + } else { + vertexBuffer.createDegenerateSeparators<Vertex>(lineAllocSize); + } +} + +/////////////////////////////////////////////////////////////////////////////// +// Simple path line approximation +/////////////////////////////////////////////////////////////////////////////// + +void pushToVector(Vector<Vertex>& vertices, float x, float y) { + // TODO: make this not yuck + vertices.push(); + Vertex* newVertex = &(vertices.editArray()[vertices.size() - 1]); + Vertex::set(newVertex, x, y); +} + +bool PathTessellator::approximatePathOutlineVertices(const SkPath& path, bool forceClose, + float sqrInvScaleX, float sqrInvScaleY, Vector<Vertex>& outputVertices) { + ATRACE_CALL(); + + // TODO: to support joins other than sharp miter, join vertices should be labelled in the + // perimeter, or resolved into more vertices. Reconsider forceClose-ing in that case. + SkPath::Iter iter(path, forceClose); + SkPoint pts[4]; + SkPath::Verb v; + while (SkPath::kDone_Verb != (v = iter.next(pts))) { + switch (v) { + case SkPath::kMove_Verb: + pushToVector(outputVertices, pts[0].x(), pts[0].y()); + ALOGV("Move to pos %f %f", pts[0].x(), pts[0].y()); + break; + case SkPath::kClose_Verb: + ALOGV("Close at pos %f %f", pts[0].x(), pts[0].y()); + break; + case SkPath::kLine_Verb: + ALOGV("kLine_Verb %f %f -> %f %f", pts[0].x(), pts[0].y(), pts[1].x(), pts[1].y()); + pushToVector(outputVertices, pts[1].x(), pts[1].y()); + break; + case SkPath::kQuad_Verb: + ALOGV("kQuad_Verb"); + recursiveQuadraticBezierVertices( + pts[0].x(), pts[0].y(), + pts[2].x(), pts[2].y(), + pts[1].x(), pts[1].y(), + sqrInvScaleX, sqrInvScaleY, outputVertices); + break; + case SkPath::kCubic_Verb: + ALOGV("kCubic_Verb"); + recursiveCubicBezierVertices( + pts[0].x(), pts[0].y(), + pts[1].x(), pts[1].y(), + pts[3].x(), pts[3].y(), + pts[2].x(), pts[2].y(), + sqrInvScaleX, sqrInvScaleY, outputVertices); + break; + default: + break; + } + } + + int size = outputVertices.size(); + if (size >= 2 && outputVertices[0].position[0] == outputVertices[size - 1].position[0] && + outputVertices[0].position[1] == outputVertices[size - 1].position[1]) { + outputVertices.pop(); + return true; + } + return false; +} + +/////////////////////////////////////////////////////////////////////////////// +// Bezier approximation +/////////////////////////////////////////////////////////////////////////////// + +void PathTessellator::recursiveCubicBezierVertices( + float p1x, float p1y, float c1x, float c1y, + float p2x, float p2y, float c2x, float c2y, + float sqrInvScaleX, float sqrInvScaleY, Vector<Vertex>& outputVertices) { + float dx = p2x - p1x; + float dy = p2y - p1y; + float d1 = fabs((c1x - p2x) * dy - (c1y - p2y) * dx); + float d2 = fabs((c2x - p2x) * dy - (c2y - p2y) * dx); + float d = d1 + d2; + + // multiplying by sqrInvScaleY/X equivalent to multiplying in dimensional scale factors + + if (d * d < THRESHOLD * THRESHOLD * (dx * dx * sqrInvScaleY + dy * dy * sqrInvScaleX)) { + // below thresh, draw line by adding endpoint + pushToVector(outputVertices, p2x, p2y); + } else { + float p1c1x = (p1x + c1x) * 0.5f; + float p1c1y = (p1y + c1y) * 0.5f; + float p2c2x = (p2x + c2x) * 0.5f; + float p2c2y = (p2y + c2y) * 0.5f; + + float c1c2x = (c1x + c2x) * 0.5f; + float c1c2y = (c1y + c2y) * 0.5f; + + float p1c1c2x = (p1c1x + c1c2x) * 0.5f; + float p1c1c2y = (p1c1y + c1c2y) * 0.5f; + + float p2c1c2x = (p2c2x + c1c2x) * 0.5f; + float p2c1c2y = (p2c2y + c1c2y) * 0.5f; + + float mx = (p1c1c2x + p2c1c2x) * 0.5f; + float my = (p1c1c2y + p2c1c2y) * 0.5f; + + recursiveCubicBezierVertices( + p1x, p1y, p1c1x, p1c1y, + mx, my, p1c1c2x, p1c1c2y, + sqrInvScaleX, sqrInvScaleY, outputVertices); + recursiveCubicBezierVertices( + mx, my, p2c1c2x, p2c1c2y, + p2x, p2y, p2c2x, p2c2y, + sqrInvScaleX, sqrInvScaleY, outputVertices); + } +} + +void PathTessellator::recursiveQuadraticBezierVertices( + float ax, float ay, + float bx, float by, + float cx, float cy, + float sqrInvScaleX, float sqrInvScaleY, Vector<Vertex>& outputVertices) { + float dx = bx - ax; + float dy = by - ay; + float d = (cx - bx) * dy - (cy - by) * dx; + + if (d * d < THRESHOLD * THRESHOLD * (dx * dx * sqrInvScaleY + dy * dy * sqrInvScaleX)) { + // below thresh, draw line by adding endpoint + pushToVector(outputVertices, bx, by); + } else { + float acx = (ax + cx) * 0.5f; + float bcx = (bx + cx) * 0.5f; + float acy = (ay + cy) * 0.5f; + float bcy = (by + cy) * 0.5f; + + // midpoint + float mx = (acx + bcx) * 0.5f; + float my = (acy + bcy) * 0.5f; + + recursiveQuadraticBezierVertices(ax, ay, mx, my, acx, acy, + sqrInvScaleX, sqrInvScaleY, outputVertices); + recursiveQuadraticBezierVertices(mx, my, bx, by, bcx, bcy, + sqrInvScaleX, sqrInvScaleY, outputVertices); + } +} + +}; // namespace uirenderer +}; // namespace android |