Tweak the threshold for conic path quads computation.
We still want it to be related to the threshold for bezier generation.
b/19903239
Change-Id: Ifdce32f1c28ecea9eac98d02c73afa948341fc7d
diff --git a/libs/hwui/PathTessellator.cpp b/libs/hwui/PathTessellator.cpp
index 547c877..38f214a 100644
--- a/libs/hwui/PathTessellator.cpp
+++ b/libs/hwui/PathTessellator.cpp
@@ -56,7 +56,7 @@
namespace android {
namespace uirenderer {
-#define OUTLINE_REFINE_THRESHOLD_SQUARED (0.5f * 0.5f)
+#define OUTLINE_REFINE_THRESHOLD 0.5f
#define ROUND_CAP_THRESH 0.25f
#define PI 3.1415926535897932f
#define MAX_DEPTH 15
@@ -739,9 +739,10 @@
// force close if we're filling the path, since fill path expects closed perimeter.
bool forceClose = paintInfo.style != SkPaint::kStroke_Style;
+ PathApproximationInfo approximationInfo(threshInvScaleX, threshInvScaleY,
+ OUTLINE_REFINE_THRESHOLD);
bool wasClosed = approximatePathOutlineVertices(path, forceClose,
- threshInvScaleX * threshInvScaleX, threshInvScaleY * threshInvScaleY,
- OUTLINE_REFINE_THRESHOLD_SQUARED, tempVertices);
+ approximationInfo, tempVertices);
if (!tempVertices.size()) {
// path was empty, return without allocating vertex buffer
@@ -819,10 +820,9 @@
// calculate outline
Vector<Vertex> outlineVertices;
- approximatePathOutlineVertices(path, true,
- paintInfo.inverseScaleX * paintInfo.inverseScaleX,
- paintInfo.inverseScaleY * paintInfo.inverseScaleY,
- OUTLINE_REFINE_THRESHOLD_SQUARED, outlineVertices);
+ PathApproximationInfo approximationInfo(paintInfo.inverseScaleX, paintInfo.inverseScaleY,
+ OUTLINE_REFINE_THRESHOLD);
+ approximatePathOutlineVertices(path, true, approximationInfo, outlineVertices);
if (!outlineVertices.size()) return;
@@ -899,9 +899,10 @@
// Simple path line approximation
///////////////////////////////////////////////////////////////////////////////
-bool PathTessellator::approximatePathOutlineVertices(const SkPath& path, float thresholdSquared,
+bool PathTessellator::approximatePathOutlineVertices(const SkPath& path, float threshold,
Vector<Vertex>& outputVertices) {
- return approximatePathOutlineVertices(path, true, 1.0f, 1.0f, thresholdSquared, outputVertices);
+ PathApproximationInfo approximationInfo(1.0f, 1.0f, threshold);
+ return approximatePathOutlineVertices(path, true, approximationInfo, outputVertices);
}
void pushToVector(Vector<Vertex>& vertices, float x, float y) {
@@ -946,8 +947,7 @@
};
bool PathTessellator::approximatePathOutlineVertices(const SkPath& path, bool forceClose,
- float sqrInvScaleX, float sqrInvScaleY, float thresholdSquared,
- Vector<Vertex>& outputVertices) {
+ const PathApproximationInfo& approximationInfo, Vector<Vertex>& outputVertices) {
ATRACE_CALL();
// TODO: to support joins other than sharp miter, join vertices should be labelled in the
@@ -978,7 +978,7 @@
pts[0].x(), pts[0].y(),
pts[2].x(), pts[2].y(),
pts[1].x(), pts[1].y(),
- sqrInvScaleX, sqrInvScaleY, thresholdSquared, outputVertices);
+ approximationInfo, outputVertices);
clockwiseEnforcer.addPoint(pts[1]);
clockwiseEnforcer.addPoint(pts[2]);
break;
@@ -989,7 +989,7 @@
pts[1].x(), pts[1].y(),
pts[3].x(), pts[3].y(),
pts[2].x(), pts[2].y(),
- sqrInvScaleX, sqrInvScaleY, thresholdSquared, outputVertices);
+ approximationInfo, outputVertices);
clockwiseEnforcer.addPoint(pts[1]);
clockwiseEnforcer.addPoint(pts[2]);
clockwiseEnforcer.addPoint(pts[3]);
@@ -998,14 +998,14 @@
ALOGV("kConic_Verb");
SkAutoConicToQuads converter;
const SkPoint* quads = converter.computeQuads(pts, iter.conicWeight(),
- thresholdSquared);
+ approximationInfo.thresholdForConicQuads);
for (int i = 0; i < converter.countQuads(); ++i) {
const int offset = 2 * i;
recursiveQuadraticBezierVertices(
quads[offset].x(), quads[offset].y(),
quads[offset+2].x(), quads[offset+2].y(),
quads[offset+1].x(), quads[offset+1].y(),
- sqrInvScaleX, sqrInvScaleY, thresholdSquared, outputVertices);
+ approximationInfo, outputVertices);
}
clockwiseEnforcer.addPoint(pts[1]);
clockwiseEnforcer.addPoint(pts[2]);
@@ -1031,12 +1031,23 @@
///////////////////////////////////////////////////////////////////////////////
// Bezier approximation
+//
+// All the inputs and outputs here are in path coordinates.
+// We convert the error threshold from screen coordinates into path coordinates.
///////////////////////////////////////////////////////////////////////////////
+// Get a threshold in path coordinates, by scaling the thresholdSquared from screen coordinates.
+// TODO: Document the math behind this algorithm.
+static inline float getThreshold(const PathApproximationInfo& info, float dx, float dy) {
+ // multiplying by sqrInvScaleY/X equivalent to multiplying in dimensional scale factors
+ float scale = (dx * dx * info.sqrInvScaleY + dy * dy * info.sqrInvScaleX);
+ return info.thresholdSquared * scale;
+}
+
void PathTessellator::recursiveCubicBezierVertices(
float p1x, float p1y, float c1x, float c1y,
float p2x, float p2y, float c2x, float c2y,
- float sqrInvScaleX, float sqrInvScaleY, float thresholdSquared,
+ const PathApproximationInfo& approximationInfo,
Vector<Vertex>& outputVertices, int depth) {
float dx = p2x - p1x;
float dy = p2y - p1y;
@@ -1044,9 +1055,8 @@
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 (depth >= MAX_DEPTH
- || d * d <= thresholdSquared * (dx * dx * sqrInvScaleY + dy * dy * sqrInvScaleX)) {
+ || d * d <= getThreshold(approximationInfo, dx, dy)) {
// below thresh, draw line by adding endpoint
pushToVector(outputVertices, p2x, p2y);
} else {
@@ -1070,11 +1080,11 @@
recursiveCubicBezierVertices(
p1x, p1y, p1c1x, p1c1y,
mx, my, p1c1c2x, p1c1c2y,
- sqrInvScaleX, sqrInvScaleY, thresholdSquared, outputVertices, depth + 1);
+ approximationInfo, outputVertices, depth + 1);
recursiveCubicBezierVertices(
mx, my, p2c1c2x, p2c1c2y,
p2x, p2y, p2c2x, p2c2y,
- sqrInvScaleX, sqrInvScaleY, thresholdSquared, outputVertices, depth + 1);
+ approximationInfo, outputVertices, depth + 1);
}
}
@@ -1082,15 +1092,15 @@
float ax, float ay,
float bx, float by,
float cx, float cy,
- float sqrInvScaleX, float sqrInvScaleY, float thresholdSquared,
+ const PathApproximationInfo& approximationInfo,
Vector<Vertex>& outputVertices, int depth) {
float dx = bx - ax;
float dy = by - ay;
+ // d is the cross product of vector (B-A) and (C-B).
float d = (cx - bx) * dy - (cy - by) * dx;
- // multiplying by sqrInvScaleY/X equivalent to multiplying in dimensional scale factors
if (depth >= MAX_DEPTH
- || d * d <= thresholdSquared * (dx * dx * sqrInvScaleY + dy * dy * sqrInvScaleX)) {
+ || d * d <= getThreshold(approximationInfo, dx, dy)) {
// below thresh, draw line by adding endpoint
pushToVector(outputVertices, bx, by);
} else {
@@ -1104,9 +1114,9 @@
float my = (acy + bcy) * 0.5f;
recursiveQuadraticBezierVertices(ax, ay, mx, my, acx, acy,
- sqrInvScaleX, sqrInvScaleY, thresholdSquared, outputVertices, depth + 1);
+ approximationInfo, outputVertices, depth + 1);
recursiveQuadraticBezierVertices(mx, my, bx, by, bcx, bcy,
- sqrInvScaleX, sqrInvScaleY, thresholdSquared, outputVertices, depth + 1);
+ approximationInfo, outputVertices, depth + 1);
}
}
diff --git a/libs/hwui/PathTessellator.h b/libs/hwui/PathTessellator.h
index ccae65b..16c8b36 100644
--- a/libs/hwui/PathTessellator.h
+++ b/libs/hwui/PathTessellator.h
@@ -27,6 +27,26 @@
namespace android {
namespace uirenderer {
+/**
+ * Structure used for threshold values in outline path tessellation.
+ *
+ * TODO: PaintInfo should store one of this object, and initialized all values in constructor
+ * depending on its type (point, line or path).
+ */
+struct PathApproximationInfo {
+ PathApproximationInfo(float invScaleX, float invScaleY, float pixelThreshold)
+ : thresholdSquared(pixelThreshold * pixelThreshold)
+ , sqrInvScaleX(invScaleX * invScaleX)
+ , sqrInvScaleY(invScaleY * invScaleY)
+ , thresholdForConicQuads(pixelThreshold * MathUtils::min(invScaleX, invScaleY) / 2.0f) {
+ };
+
+ const float thresholdSquared;
+ const float sqrInvScaleX;
+ const float sqrInvScaleY;
+ const float thresholdForConicQuads;
+};
+
class PathTessellator {
public:
/**
@@ -85,16 +105,15 @@
* Approximates a convex outline into a clockwise Vector of 2d vertices.
*
* @param path The outline to be approximated
- * @param thresholdSquared The threshold of acceptable error (in pixels) when approximating
+ * @param threshold The threshold of acceptable error (in pixels) when approximating
* @param outputVertices An empty Vector which will be populated with the output
*/
- static bool approximatePathOutlineVertices(const SkPath &path, float thresholdSquared,
+ static bool approximatePathOutlineVertices(const SkPath &path, float threshold,
Vector<Vertex> &outputVertices);
private:
static bool approximatePathOutlineVertices(const SkPath &path, bool forceClose,
- float sqrInvScaleX, float sqrInvScaleY, float thresholdSquared,
- Vector<Vertex> &outputVertices);
+ const PathApproximationInfo& approximationInfo, Vector<Vertex> &outputVertices);
/*
endpoints a & b,
@@ -104,7 +123,7 @@
float ax, float ay,
float bx, float by,
float cx, float cy,
- float sqrInvScaleX, float sqrInvScaleY, float thresholdSquared,
+ const PathApproximationInfo& approximationInfo,
Vector<Vertex> &outputVertices, int depth = 0);
/*
@@ -116,7 +135,7 @@
float c1x, float c1y,
float p2x, float p2y,
float c2x, float c2y,
- float sqrInvScaleX, float sqrInvScaleY, float thresholdSquared,
+ const PathApproximationInfo& approximationInfo,
Vector<Vertex> &outputVertices, int depth = 0);
};
diff --git a/libs/hwui/TessellationCache.cpp b/libs/hwui/TessellationCache.cpp
index 704a691..9df1f0d 100644
--- a/libs/hwui/TessellationCache.cpp
+++ b/libs/hwui/TessellationCache.cpp
@@ -226,9 +226,9 @@
// tessellate caster outline into a 2d polygon
Vector<Vertex> casterVertices2d;
- const float casterRefinementThresholdSquared = 4.0f;
+ const float casterRefinementThreshold = 2.0f;
PathTessellator::approximatePathOutlineVertices(*casterPerimeter,
- casterRefinementThresholdSquared, casterVertices2d);
+ casterRefinementThreshold, casterVertices2d);
// Shadow requires CCW for now. TODO: remove potential double-reverse
reverseVertexArray(casterVertices2d.editArray(), casterVertices2d.size());