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-rw-r--r--gm/arcto.cpp86
-rw-r--r--include/core/SkPath.h52
-rw-r--r--src/core/SkPath.cpp107
-rw-r--r--src/utils/SkParsePath.cpp12
4 files changed, 253 insertions, 4 deletions
diff --git a/gm/arcto.cpp b/gm/arcto.cpp
new file mode 100644
index 0000000000..900c6b30ea
--- /dev/null
+++ b/gm/arcto.cpp
@@ -0,0 +1,86 @@
+/*
+ * Copyright 2016 Google Inc.
+ *
+ * Use of this source code is governed by a BD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#include "gm.h"
+#include "SkParsePath.h"
+#include "SkPath.h"
+
+/*
+The arcto test below should draw the same as this SVG:
+(Note that Skia's arcTo Direction parameter value is opposite SVG's sweep value, e.g. 0 / 1)
+
+<svg width="500" height="600">
+<path d="M 50,100 A50,50, 0,0,1, 150,200" style="stroke:#660000; fill:none; stroke-width:2" />
+<path d="M100,100 A50,100, 0,0,1, 200,200" style="stroke:#660000; fill:none; stroke-width:2" />
+<path d="M150,100 A50,50, 45,0,1, 250,200" style="stroke:#660000; fill:none; stroke-width:2" />
+<path d="M200,100 A50,100, 45,0,1, 300,200" style="stroke:#660000; fill:none; stroke-width:2" />
+
+<path d="M150,200 A50,50, 0,1,0, 150,300" style="stroke:#660000; fill:none; stroke-width:2" />
+<path d="M200,200 A50,100, 0,1,0, 200,300" style="stroke:#660000; fill:none; stroke-width:2" />
+<path d="M250,200 A50,50, 45,1,0, 250,300" style="stroke:#660000; fill:none; stroke-width:2" />
+<path d="M300,200 A50,100, 45,1,0, 300,300" style="stroke:#660000; fill:none; stroke-width:2" />
+
+<path d="M250,400 A120,80 0 0,0 250,500"
+ fill="none" stroke="red" stroke-width="5" />
+
+<path d="M250,400 A120,80 0 1,1 250,500"
+ fill="none" stroke="green" stroke-width="5"/>
+
+<path d="M250,400 A120,80 0 1,0 250,500"
+ fill="none" stroke="purple" stroke-width="5"/>
+
+<path d="M250,400 A120,80 0 0,1 250,500"
+ fill="none" stroke="blue" stroke-width="5"/>
+</svg>
+ */
+
+DEF_SIMPLE_GM(arcto, canvas, 500, 600) {
+ SkPaint paint;
+ paint.setAntiAlias(true);
+ paint.setStyle(SkPaint::kStroke_Style);
+ paint.setStrokeWidth(2);
+ paint.setColor(0xFF660000);
+ canvas->scale(2, 2);
+ SkRect oval = SkRect::MakeXYWH(100, 100, 100, 100);
+ SkPath svgArc;
+
+ for (int angle = 0; angle <= 45; angle += 45) {
+ for (int oHeight = 2; oHeight >= 1; --oHeight) {
+ SkScalar ovalHeight = oval.height() / oHeight;
+ svgArc.moveTo(oval.fLeft, oval.fTop);
+ svgArc.arcTo(oval.width() / 2, ovalHeight, SkIntToScalar(angle), SkPath::kSmall_ArcSize,
+ SkPath::kCW_Direction, oval.right(), oval.bottom());
+ canvas->drawPath(svgArc, paint);
+ svgArc.reset();
+
+ svgArc.moveTo(oval.fLeft + 100, oval.fTop + 100);
+ svgArc.arcTo(oval.width() / 2, ovalHeight, SkIntToScalar(angle), SkPath::kLarge_ArcSize,
+ SkPath::kCCW_Direction, oval.right(), oval.bottom() + 100);
+ canvas->drawPath(svgArc, paint);
+ oval.offset(50, 0);
+ svgArc.reset();
+
+ }
+ }
+
+ paint.setStrokeWidth(5);
+ const SkColor purple = 0xFF800080;
+ const SkColor darkgreen = 0xFF008000;
+ const SkColor colors[] = { SK_ColorRED, darkgreen, purple, SK_ColorBLUE };
+ const char* arcstrs[] = {
+ "M250,400 A120,80 0 0,0 250,500",
+ "M250,400 A120,80 0 1,1 250,500",
+ "M250,400 A120,80 0 1,0 250,500",
+ "M250,400 A120,80 0 0,1 250,500"
+ };
+ int cIndex = 0;
+ for (const char* arcstr : arcstrs) {
+ SkParsePath::FromSVGString(arcstr, &svgArc);
+ paint.setColor(colors[cIndex++]);
+ canvas->drawPath(svgArc, paint);
+ }
+}
diff --git a/include/core/SkPath.h b/include/core/SkPath.h
index 6952719815..7c6fd35d5a 100644
--- a/include/core/SkPath.h
+++ b/include/core/SkPath.h
@@ -499,10 +499,12 @@ public:
this->arcTo(p1.fX, p1.fY, p2.fX, p2.fY, radius);
}
- /** Close the current contour. If the current point is not equal to the
- first point of the contour, a line segment is automatically added.
- */
- void close();
+ enum ArcSize {
+ /** the smaller of the two possible SVG arcs. */
+ kSmall_ArcSize,
+ /** the larger of the two possible SVG arcs. */
+ kLarge_ArcSize,
+ };
enum Direction {
/** clockwise direction for adding closed contours */
@@ -512,6 +514,48 @@ public:
};
/**
+ * Append an elliptical arc from the current point in the format used by SVG.
+ * The center of the ellipse is computed to satisfy the constraints below.
+ *
+ * @param rx,ry The radii in the x and y directions respectively.
+ * @param xAxisRotate The angle in degrees relative to the x-axis.
+ * @param largeArc Determines whether the smallest or largest arc possible
+ * is drawn.
+ * @param sweep Determines if the arc should be swept in an anti-clockwise or
+ * clockwise direction. Note that this enum value is opposite the SVG
+ * arc sweep value.
+ * @param x,y The destination coordinates.
+ */
+ void arcTo(SkScalar rx, SkScalar ry, SkScalar xAxisRotate, ArcSize largeArc,
+ Direction sweep, SkScalar x, SkScalar y);
+
+ void arcTo(const SkPoint r, SkScalar xAxisRotate, ArcSize largeArc, Direction sweep,
+ const SkPoint xy) {
+ this->arcTo(r.fX, r.fY, xAxisRotate, largeArc, sweep, xy.fX, xy.fY);
+ }
+
+ /** Same as arcTo format used by SVG, but the destination coordinate is relative to the
+ * last point on this contour. If there is no previous point, then a
+ * moveTo(0,0) is inserted automatically.
+ *
+ * @param rx,ry The radii in the x and y directions respectively.
+ * @param xAxisRotate The angle in degrees relative to the x-axis.
+ * @param largeArc Determines whether the smallest or largest arc possible
+ * is drawn.
+ * @param sweep Determines if the arc should be swept in an anti-clockwise or
+ * clockwise direction. Note that this enum value is opposite the SVG
+ * arc sweep value.
+ * @param dx,dy The destination coordinates relative to the last point.
+ */
+ void rArcTo(SkScalar rx, SkScalar ry, SkScalar xAxisRotate, ArcSize largeArc,
+ Direction sweep, SkScalar dx, SkScalar dy);
+
+ /** Close the current contour. If the current point is not equal to the
+ first point of the contour, a line segment is automatically added.
+ */
+ void close();
+
+ /**
* Returns whether or not a fill type is inverted
*
* kWinding_FillType -> false
diff --git a/src/core/SkPath.cpp b/src/core/SkPath.cpp
index c77a25b4aa..40ca50b5ca 100644
--- a/src/core/SkPath.cpp
+++ b/src/core/SkPath.cpp
@@ -1257,6 +1257,113 @@ void SkPath::arcTo(const SkRect& oval, SkScalar startAngle, SkScalar sweepAngle,
}
}
+// This converts the SVG arc to conics.
+// Partly adapted from Niko's code in kdelibs/kdecore/svgicons.
+// Then transcribed from webkit/chrome's SVGPathNormalizer::decomposeArcToCubic()
+// See also SVG implementation notes:
+// http://www.w3.org/TR/SVG/implnote.html#ArcConversionEndpointToCenter
+// Note that arcSweep bool value is flipped from the original implementation.
+void SkPath::arcTo(SkScalar rx, SkScalar ry, SkScalar angle, SkPath::ArcSize arcLarge,
+ SkPath::Direction arcSweep, SkScalar x, SkScalar y) {
+ SkPoint srcPts[2];
+ this->getLastPt(&srcPts[0]);
+ // If rx = 0 or ry = 0 then this arc is treated as a straight line segment (a "lineto")
+ // joining the endpoints.
+ // http://www.w3.org/TR/SVG/implnote.html#ArcOutOfRangeParameters
+ if (!rx || !ry) {
+ return;
+ }
+ // If the current point and target point for the arc are identical, it should be treated as a
+ // zero length path. This ensures continuity in animations.
+ srcPts[1].set(x, y);
+ if (srcPts[0] == srcPts[1]) {
+ return;
+ }
+ rx = SkScalarAbs(rx);
+ ry = SkScalarAbs(ry);
+ SkVector midPointDistance = srcPts[0] - srcPts[1];
+ midPointDistance *= 0.5f;
+
+ SkMatrix pointTransform;
+ pointTransform.setRotate(-angle);
+
+ SkPoint transformedMidPoint;
+ pointTransform.mapPoints(&transformedMidPoint, &midPointDistance, 1);
+ SkScalar squareRx = rx * rx;
+ SkScalar squareRy = ry * ry;
+ SkScalar squareX = transformedMidPoint.fX * transformedMidPoint.fX;
+ SkScalar squareY = transformedMidPoint.fY * transformedMidPoint.fY;
+
+ // Check if the radii are big enough to draw the arc, scale radii if not.
+ // http://www.w3.org/TR/SVG/implnote.html#ArcCorrectionOutOfRangeRadii
+ SkScalar radiiScale = squareX / squareRx + squareY / squareRy;
+ if (radiiScale > 1) {
+ radiiScale = SkScalarSqrt(radiiScale);
+ rx *= radiiScale;
+ ry *= radiiScale;
+ }
+
+ pointTransform.setScale(1 / rx, 1 / ry);
+ pointTransform.preRotate(-angle);
+
+ SkPoint unitPts[2];
+ pointTransform.mapPoints(unitPts, srcPts, (int) SK_ARRAY_COUNT(unitPts));
+ SkVector delta = unitPts[1] - unitPts[0];
+
+ SkScalar d = delta.fX * delta.fX + delta.fY * delta.fY;
+ SkScalar scaleFactorSquared = SkTMax(1 / d - 0.25f, 0.f);
+
+ SkScalar scaleFactor = SkScalarSqrt(scaleFactorSquared);
+ if (SkToBool(arcSweep) != SkToBool(arcLarge)) { // flipped from the original implementation
+ scaleFactor = -scaleFactor;
+ }
+ delta.scale(scaleFactor);
+ SkPoint centerPoint = unitPts[0] + unitPts[1];
+ centerPoint *= 0.5f;
+ centerPoint.offset(-delta.fY, delta.fX);
+ unitPts[0] -= centerPoint;
+ unitPts[1] -= centerPoint;
+ SkScalar theta1 = SkScalarATan2(unitPts[0].fY, unitPts[0].fX);
+ SkScalar theta2 = SkScalarATan2(unitPts[1].fY, unitPts[1].fX);
+ SkScalar thetaArc = theta2 - theta1;
+ if (thetaArc < 0 && !arcSweep) { // arcSweep flipped from the original implementation
+ thetaArc += SK_ScalarPI * 2;
+ } else if (thetaArc > 0 && arcSweep) { // arcSweep flipped from the original implementation
+ thetaArc -= SK_ScalarPI * 2;
+ }
+ pointTransform.setRotate(angle);
+ pointTransform.preScale(rx, ry);
+
+ int segments = SkScalarCeilToInt(SkScalarAbs(thetaArc / (SK_ScalarPI / 2)));
+ SkScalar thetaWidth = thetaArc / segments;
+ SkScalar t = SkScalarTan(0.5f * thetaWidth);
+ if (!SkScalarIsFinite(t)) {
+ return;
+ }
+ SkScalar startTheta = theta1;
+ SkScalar w = SkScalarSqrt(SK_ScalarHalf + SkScalarCos(thetaWidth) * SK_ScalarHalf);
+ for (int i = 0; i < segments; ++i) {
+ SkScalar endTheta = startTheta + thetaWidth;
+ SkScalar cosEndTheta, sinEndTheta = SkScalarSinCos(endTheta, &cosEndTheta);
+
+ unitPts[1].set(cosEndTheta, sinEndTheta);
+ unitPts[1] += centerPoint;
+ unitPts[0] = unitPts[1];
+ unitPts[0].offset(t * sinEndTheta, -t * cosEndTheta);
+ SkPoint mapped[2];
+ pointTransform.mapPoints(mapped, unitPts, (int) SK_ARRAY_COUNT(unitPts));
+ this->conicTo(mapped[0], mapped[1], w);
+ startTheta = endTheta;
+ }
+}
+
+void SkPath::rArcTo(SkScalar rx, SkScalar ry, SkScalar xAxisRotate, SkPath::ArcSize largeArc,
+ SkPath::Direction sweep, SkScalar dx, SkScalar dy) {
+ SkPoint currentPoint;
+ this->getLastPt(&currentPoint);
+ this->arcTo(rx, ry, xAxisRotate, largeArc, sweep, currentPoint.fX + dx, currentPoint.fY + dy);
+}
+
void SkPath::addArc(const SkRect& oval, SkScalar startAngle, SkScalar sweepAngle) {
if (oval.isEmpty() || 0 == sweepAngle) {
return;
diff --git a/src/utils/SkParsePath.cpp b/src/utils/SkParsePath.cpp
index 3eb9e1ef79..c0f39aa06f 100644
--- a/src/utils/SkParsePath.cpp
+++ b/src/utils/SkParsePath.cpp
@@ -64,6 +64,7 @@ static const char* find_scalar(const char str[], SkScalar* value,
if (isRelative) {
*value += relative;
}
+ str = skip_sep(str);
return str;
}
@@ -156,6 +157,17 @@ bool SkParsePath::FromSVGString(const char data[], SkPath* result) {
lastc = points[0];
c = points[1];
break;
+ case 'A': {
+ SkPoint radii;
+ data = find_points(data, &radii, 1, false, nullptr);
+ SkScalar angle, largeArc, sweep;
+ data = find_scalar(data, &angle, false, 0);
+ data = find_scalar(data, &largeArc, false, 0);
+ data = find_scalar(data, &sweep, false, 0);
+ data = find_points(data, &points[0], 1, relative, &c);
+ path.arcTo(radii, angle, (SkPath::ArcSize) SkToBool(largeArc),
+ (SkPath::Direction) !SkToBool(sweep), points[0]);
+ } break;
case 'Z':
path.close();
#if 0 // !!! still a bug?
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-25 22:24:43 +0000