compose and combine maskfilters

Bug: skia:
Change-Id: Id470124021d00ee25cf4ae392a4ee345ced84110
Reviewed-on: https://skia-review.googlesource.com/97760
Reviewed-by: Mike Klein <mtklein@chromium.org>
Reviewed-by: Florin Malita <fmalita@chromium.org>
Commit-Queue: Mike Reed <reed@google.com>

1 files changed, 91 insertions, 2 deletions

diff --git a/gm/shadermaskfilter.cpp b/gm/shadermaskfilter.cpp
index 35d8fd7040..3545e557e5 100644
--- a/gm/shadermaskfilter.cpp
+++ b/gm/shadermaskfilter.cpp
@@ -7,16 +7,21 @@
 
 #include "gm.h"
 #include "sk_tool_utils.h"
+#include "SkBlurMaskFilter.h"
 #include "SkCanvas.h"
 #include "SkImage.h"
 #include "SkShaderMaskFilter.h"
 
 static void draw_masked_image(SkCanvas* canvas, const SkImage* image, SkScalar x, SkScalar y,
-                              const SkImage* mask) {
+                              const SkImage* mask, sk_sp<SkMaskFilter> outer = nullptr) {
     SkMatrix matrix = SkMatrix::MakeScale(SkIntToScalar(image->width()) / mask->width(),
                                           SkIntToScalar(image->height() / mask->height()));
     SkPaint paint;
-    paint.setMaskFilter(SkShaderMaskFilter::Make(mask->makeShader(&matrix)));
+    auto mf = SkShaderMaskFilter::Make(mask->makeShader(&matrix));
+    if (outer) {
+        mf = SkMaskFilter::MakeCompose(outer, mf);
+    }
+    paint.setMaskFilter(mf);
     canvas->drawImage(image, x, y, &paint);
 }
 
@@ -49,9 +54,93 @@ DEF_SIMPLE_GM(shadermaskfilter_image, canvas, 512, 512) {
 
     auto image = GetResourceAsImage("images/mandrill_128.png");
     auto mask = GetResourceAsImage("images/color_wheel.png");
+    auto blurmf = SkBlurMaskFilter::Make(kNormal_SkBlurStyle, 5);
 
     canvas->drawImage(image, 10, 10, nullptr);
     canvas->drawImage(mask, 10 + image->width() + 10.f, 10, nullptr);
 
     draw_masked_image(canvas, image.get(), 10, 10 + image->height() + 10.f, mask.get());
+    draw_masked_image(canvas, image.get(), 10 + image->width() + 10.f, 10 + image->height() + 10.f,
+                      mask.get(), blurmf);
+}
+
+///////////////////////////////////////////////////////////////////////////////////////////////////
+
+namespace {
+enum class SkAlphaBlendMode {
+    kClear,    // 0
+    kSrc,      // src
+    kDst,      // dst
+    kOver,     // src + dst - src*dst
+    kIn,       // src * dst
+    kSrcOut,   // src * (1 - dst)
+    kDstOut,   // dst * (1 - src)
+    kXor,      // src + dst - 2*src*dst
+    kPlus,     // src + dst
+
+    kLast = kPlus,
+};
+
+const SkBlendMode gAlphaToBlendMode[] = {
+    SkBlendMode::kClear,    // SkAlphaBlendMode::kClear
+    SkBlendMode::kSrc,      // SkAlphaBlendMode::kSrc
+    SkBlendMode::kDst,      // SkAlphaBlendMode::kDst
+    SkBlendMode::kSrcOver,  // SkAlphaBlendMode::kOver
+    SkBlendMode::kSrcIn,    // SkAlphaBlendMode::kIn
+    SkBlendMode::kSrcOut,   // SkAlphaBlendMode::kSrcOut
+    SkBlendMode::kDstOut,   // SkAlphaBlendMode::kDstOut
+    SkBlendMode::kXor,      // SkAlphaBlendMode::kXor
+    SkBlendMode::kPlus,     // SkAlphaBlendMode::kPlus
+};
+}
+
+#include "SkPictureRecorder.h"
+#include "SkPath.h"
+static sk_sp<SkMaskFilter> make_path_mf(const SkPath& path, unsigned alpha) {
+    SkPaint paint;
+    paint.setAntiAlias(true);
+    paint.setAlpha(alpha);
+
+    SkPictureRecorder recorder;
+    recorder.beginRecording(1000, 1000)->drawPath(path, paint);
+    auto shader = SkShader::MakePictureShader(recorder.finishRecordingAsPicture(),
+                                              SkShader::kClamp_TileMode, SkShader::kClamp_TileMode,
+                                              nullptr, nullptr);
+    return SkShaderMaskFilter::Make(shader);
+}
+
+DEF_SIMPLE_GM(combinemaskfilter, canvas, 340, 340) {
+    const SkRect r = { 0, 0, 100, 100 };
+
+    const SkRect r2 = r.makeOutset(1.5f, 1.5f);
+    SkPaint paint2;
+    paint2.setStyle(SkPaint::kStroke_Style);
+
+    SkPath pathA;
+    pathA.moveTo(r.fLeft, r.fBottom);
+    pathA.lineTo(r.fRight, r.fTop);
+    pathA.lineTo(r.fRight, r.fBottom);
+    auto mfA = make_path_mf(pathA, 1 * 0xFF / 3);
+
+    SkPath pathB;
+    pathB.moveTo(r.fLeft, r.fTop);
+    pathB.lineTo(r.fRight, r.fBottom);
+    pathB.lineTo(r.fLeft, r.fBottom);
+    auto mfB = make_path_mf(pathB, 2 * 0xFF / 3);
+
+    canvas->translate(10, 10);
+    canvas->save();
+    for (int i = 0; i < 9; ++i) {
+        SkPaint paint;
+        paint.setMaskFilter(SkMaskFilter::MakeCombine(mfA, mfB, gAlphaToBlendMode[i]));
+        canvas->drawRect(r2, paint2);
+        canvas->drawRect(r, paint);
+        canvas->translate(r.width() + 10, 0);
+        if ((i % 3) == 2) {
+            canvas->restore();
+            canvas->translate(0, r.height() + 10);
+            canvas->save();
+        }
+    }
+    canvas->restore();
 }