Implement support for expanding crop rects in image filters

NOTE: this patch set is based on https://codereview.chromium.org/189913021/,
and needs that patch to land first.

Until now, crop rects in Skia have only been able to reduce
the size of the destination bounds, but not expand them.
SVG semantics require the latter as well. The heart of
the change is in applyCropRect(), which now assigns each
edge, instead of doing an intersection with the crop rect.

In order to support this (and still work well with tiled
drawing) we need to clip the resulting crop rect to the
clipping region of the filters. This uses the Context struct
previously landed from https://codereview.chromium.org/189913021/.

Many of the pixel loops are not yet ready to handle a
destination rect larger than the source rect. So we provide
a convenience version of applyCropRect() which creates an
offscreen and pads it out with transparent black. Once the
pixel loops and shaders have been fixed to support larger
destination bounds, they should be switched back to the
non-drawing version of applyCropRect().

BUG=skia:
R=bsalomon@google.com, reed@google.com

Review URL: https://codereview.chromium.org/198003008

git-svn-id: http://skia.googlecode.com/svn/trunk@13805 2bbb7eff-a529-9590-31e7-b0007b416f81

2 files changed, 171 insertions, 3 deletions

diff --git a/gm/imagefilterscropexpand.cpp b/gm/imagefilterscropexpand.cpp
new file mode 100644
index 0000000000..9373696773
--- /dev/null
+++ b/gm/imagefilterscropexpand.cpp
@@ -0,0 +1,170 @@
+/*
+ * Copyright 2014 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#include "gm.h"
+#include "SkCanvas.h"
+#include "SkColorFilter.h"
+#include "SkColorPriv.h"
+#include "SkShader.h"
+
+#include "SkBitmapSource.h"
+#include "SkBlurImageFilter.h"
+#include "SkColorMatrixFilter.h"
+#include "SkDisplacementMapEffect.h"
+#include "SkDropShadowImageFilter.h"
+#include "SkGradientShader.h"
+#include "SkMorphologyImageFilter.h"
+#include "SkColorFilterImageFilter.h"
+#include "SkMergeImageFilter.h"
+#include "SkOffsetImageFilter.h"
+
+///////////////////////////////////////////////////////////////////////////////
+
+class ImageFiltersCropExpandGM : public skiagm::GM {
+public:
+    ImageFiltersCropExpandGM () {}
+
+protected:
+
+    virtual SkString onShortName() {
+        return SkString("imagefilterscropexpand");
+    }
+
+    virtual SkISize onISize() { return SkISize::Make(570, 650); }
+
+    void make_checkerboard(SkBitmap* bitmap) {
+        bitmap->allocN32Pixels(64, 64);
+        SkCanvas canvas(*bitmap);
+        canvas.clear(0xFFFF0000);
+        SkPaint darkPaint;
+        darkPaint.setColor(0xFF404040);
+        SkPaint lightPaint;
+        lightPaint.setColor(0xFFA0A0A0);
+        for (int y = 8; y < 48; y += 16) {
+            for (int x = 8; x < 48; x += 16) {
+                canvas.save();
+                canvas.translate(SkIntToScalar(x), SkIntToScalar(y));
+                canvas.drawRect(SkRect::MakeXYWH(0, 0, 8, 8), darkPaint);
+                canvas.drawRect(SkRect::MakeXYWH(8, 0, 8, 8), lightPaint);
+                canvas.drawRect(SkRect::MakeXYWH(0, 8, 8, 8), lightPaint);
+                canvas.drawRect(SkRect::MakeXYWH(8, 8, 8, 8), darkPaint);
+                canvas.restore();
+            }
+        }
+    }
+
+    void make_gradient_circle(int width, int height, SkBitmap* bitmap) {
+        SkScalar x = SkIntToScalar(width / 2);
+        SkScalar y = SkIntToScalar(height / 2);
+        SkScalar radius = SkMinScalar(x, y) * 0.8f;
+        bitmap->allocN32Pixels(width, height);
+        SkCanvas canvas(*bitmap);
+        canvas.clear(0x00000000);
+        SkColor colors[2];
+        colors[0] = SK_ColorWHITE;
+        colors[1] = SK_ColorBLACK;
+        SkAutoTUnref<SkShader> shader(
+            SkGradientShader::CreateRadial(SkPoint::Make(x, y), radius, colors, NULL, 2,
+                                           SkShader::kClamp_TileMode)
+        );
+        SkPaint paint;
+        paint.setShader(shader);
+        canvas.drawCircle(x, y, radius, paint);
+    }
+
+    static void draw(SkCanvas* canvas, const SkBitmap& bitmap, const SkRect& rect, SkImageFilter* filter) {
+        SkPaint paint;
+        paint.setImageFilter(filter)->unref();
+        canvas->saveLayer(&rect, &paint);
+        canvas->drawBitmap(bitmap, 0, 0);
+        canvas->restore();
+        
+        SkPaint strokePaint;
+        strokePaint.setColor(0xFFFF0000);
+        strokePaint.setStyle(SkPaint::kStroke_Style);
+        canvas->drawRect(rect, strokePaint);
+
+        canvas->translate(SkIntToScalar(80), 0);
+    }
+
+    virtual void onDraw(SkCanvas* canvas) {
+        SkAutoTUnref<SkColorFilter> cf(
+            SkColorFilter::CreateModeFilter(SK_ColorBLUE, SkXfermode::kSrcIn_Mode));
+        SkImageFilter::CropRect crop_rect(
+            SkRect::Make(SkIRect::MakeXYWH(10, 10, 44, 44)),
+            SkImageFilter::CropRect::kHasAll_CropEdge);
+
+        SkBitmap gradient_circle, checkerboard;
+        make_gradient_circle(64, 64, &gradient_circle);
+        make_checkerboard(&checkerboard);
+
+        SkAutoTUnref<SkImageFilter> gradient_circle_source(
+            SkBitmapSource::Create(gradient_circle));
+        SkAutoTUnref<SkImageFilter> noop_cropped(
+            SkOffsetImageFilter::Create(0, 0, NULL, &crop_rect));
+        SkScalar sk255 = SkIntToScalar(255);
+        SkScalar matrix[20] = { 1, 0, 0, 0, 0,
+                                0, 1, 0, 0, sk255,
+                                0, 0, 1, 0, 0,
+                                0, 0, 0, 0, sk255 };
+        SkAutoTUnref<SkColorFilter> cf_alpha_trans(SkColorMatrixFilter::Create(matrix));
+
+        SkRect r = SkRect::MakeWH(SkIntToScalar(64), SkIntToScalar(64));
+        SkScalar MARGIN = SkIntToScalar(12);
+
+        SkIRect bounds;
+        r.roundOut(&bounds);
+
+        SkPaint paint;
+        canvas->translate(MARGIN, MARGIN);
+        for (int outset = -15; outset <= 20; outset += 5) {
+            canvas->save();
+            SkRect rect = crop_rect.rect();
+            rect.outset(SkIntToScalar(outset),
+                        SkIntToScalar(outset));
+            SkImageFilter::CropRect big_rect(rect, SkImageFilter::CropRect::kHasAll_CropEdge);
+            
+            draw(canvas, checkerboard, rect, SkColorFilterImageFilter::Create(
+                cf_alpha_trans, noop_cropped.get(), &big_rect));
+
+            draw(canvas, checkerboard, rect, SkBlurImageFilter::Create(
+                8.0f, 8.0f, noop_cropped.get(), &big_rect));
+
+            draw(canvas, checkerboard, rect, SkDilateImageFilter::Create(
+                2, 2, noop_cropped.get(), &big_rect));
+
+            draw(canvas, checkerboard, rect, SkErodeImageFilter::Create(
+                2, 2, noop_cropped.get(), &big_rect));
+
+            draw(canvas, checkerboard, rect, SkDropShadowImageFilter::Create(
+                SkIntToScalar(10), SkIntToScalar(10), SkIntToScalar(3), SkIntToScalar(3),
+                SK_ColorBLUE, noop_cropped.get(), &big_rect));
+
+            draw(canvas, checkerboard, rect, SkDisplacementMapEffect::Create(
+                SkDisplacementMapEffect::kR_ChannelSelectorType,
+                SkDisplacementMapEffect::kR_ChannelSelectorType,
+                SkIntToScalar(12),
+                gradient_circle_source.get(),
+                noop_cropped.get(),
+                &big_rect));
+
+            draw(canvas, checkerboard, rect, SkOffsetImageFilter::Create(
+                SkIntToScalar(-8), SkIntToScalar(16), noop_cropped.get(), &big_rect));
+
+            canvas->restore();
+            canvas->translate(0, SkIntToScalar(80));
+        }
+    }
+
+private:
+    typedef GM INHERITED;
+};
+
+///////////////////////////////////////////////////////////////////////////////
+
+static skiagm::GM* MyFactory(void*) { return new ImageFiltersCropExpandGM; }
+static skiagm::GMRegistry reg(MyFactory);
diff --git a/gm/imagefiltersgraph.cpp b/gm/imagefiltersgraph.cpp
index bc34e656d0..8885f0d231 100644
--- a/gm/imagefiltersgraph.cpp
+++ b/gm/imagefiltersgraph.cpp
@@ -39,9 +39,7 @@ public:
         }
 
         SkIRect bounds;
-        source.getBounds(&bounds);
-
-        if (!this->applyCropRect(&bounds, ctx.ctm())) {
+        if (!this->applyCropRect(ctx, proxy, source, &srcOffset, &bounds, &source)) {
             return false;
         }