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Commit f1f99fd4 authored by Chris Craik's avatar Chris Craik Committed by Android Git Automerger
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am 830ac05c: am 7b2c58b3: am da28c868: Merge "Fix round cap approximation to... 

am 830ac05c: am 7b2c58b3: am da28c868: Merge "Fix round cap approximation to understand scale" into mnc-dev

* commit '830ac05c':
  Fix round cap approximation to understand scale
parents 072930f9 830ac05c

libs/hwui/PathTessellator.cpp

+3 −5
Original line number Original line Diff line number Diff line
@@ -152,13 +152,11 @@ public: 
     */

     */

    inline int capExtraDivisions() const {

    inline int capExtraDivisions() const {

        if (cap == SkPaint::kRound_Cap) {

        if (cap == SkPaint::kRound_Cap) {

            // always use 2 points for hairline

            if (halfStrokeWidth == 0.0f) return 2;

            if (halfStrokeWidth == 0.0f) return 2;





            // ROUND_CAP_THRESH is the maximum error for polygonal approximation of the round cap

            float threshold = MathUtils::min(inverseScaleX, inverseScaleY) * ROUND_CAP_THRESH;

            const float errConst = (-ROUND_CAP_THRESH / halfStrokeWidth + 1);

            return MathUtils::divisionsNeededToApproximateArc(halfStrokeWidth, PI, threshold);

            const float targetCosVal = 2 * errConst * errConst - 1;

            int neededDivisions = (int)(ceilf(PI / acos(targetCosVal)/2)) * 2;

            return neededDivisions;

        }

        }

        return 0;

        return 0;

    }

    }

libs/hwui/utils/MathUtils.h

+15 −0
Original line number Original line Diff line number Diff line
@@ -16,6 +16,8 @@ 
#ifndef MATHUTILS_H

#ifndef MATHUTILS_H

#define MATHUTILS_H

#define MATHUTILS_H





#include <math.h>



namespace android {

namespace android {

namespace uirenderer {

namespace uirenderer {
@@ -62,6 +64,19 @@ public: 
        return scale;

        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) {

    inline static bool areEqual(float valueA, float valueB) {

        return isZero(valueA - valueB);

        return isZero(valueA - valueB);

    }

    }