Fix round cap approximation to understand scale (ff29b5a5) · Commits · e / os / android_frameworks_base

libs/hwui/PathTessellator.cpp

+3 −5

Original line number	Diff line number	Diff line
		@@ -151,13 +151,11 @@ public:
		*/
		inline int capExtraDivisions() const {
		if (cap == SkPaint::kRound_Cap) {
		// always use 2 points for hairline
		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;
		float threshold = MathUtils::min(inverseScaleX, inverseScaleY) * ROUND_CAP_THRESH;
		return MathUtils::divisionsNeededToApproximateArc(halfStrokeWidth, PI, threshold);
		}
		return 0;
		}

+15 −0

Original line number	Diff line number	Diff line
		@@ -16,6 +16,8 @@
		#ifndef MATHUTILS_H
		#define MATHUTILS_H

		#include <math.h>

		namespace android {
		namespace uirenderer {

		@@ -62,6 +64,19 @@ public:
		return scale;
		}

		/**
		* Returns the number of points (beyond two, the start and end) needed to form a polygonal
		* approximation of an arc, with a given threshold value.
		*/
		inline static int divisionsNeededToApproximateArc(float radius,
		float angleInRads, float threshold) {
		const float errConst = (-threshold / radius + 1);
		const float targetCosVal = 2 * errConst * errConst - 1;

		// needed divisions are rounded up from approximation
		return (int)(ceilf(angleInRads / acos(targetCosVal)/2)) * 2;
		}

		inline static bool areEqual(float valueA, float valueB) {
		return isZero(valueA - valueB);
		}