add shadermaskfilter

next steps:
- gpu impl (will look a lot like shader's asFragProcessor
- special-case rect-input (?)
- explore stages w/ mtklein

Bug: skia:7500
Change-Id: I71089e421d32443a3ddded6967b3e5bc67ed43f2
Reviewed-on: https://skia-review.googlesource.com/95104
Commit-Queue: Mike Reed <reed@google.com>
Reviewed-by: Florin Malita <fmalita@chromium.org>
Reviewed-by: Brian Salomon <bsalomon@google.com>

1 files changed, 57 insertions, 0 deletions

diff --git a/gm/shadermaskfilter.cpp b/gm/shadermaskfilter.cpp
new file mode 100644
index 0000000000..35d8fd7040
--- /dev/null
+++ b/gm/shadermaskfilter.cpp
@@ -0,0 +1,57 @@
+/*
+ * Copyright 2018 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 "sk_tool_utils.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) {
+    SkMatrix matrix = SkMatrix::MakeScale(SkIntToScalar(image->width()) / mask->width(),
+                                          SkIntToScalar(image->height() / mask->height()));
+    SkPaint paint;
+    paint.setMaskFilter(SkShaderMaskFilter::Make(mask->makeShader(&matrix)));
+    canvas->drawImage(image, x, y, &paint);
+}
+
+#include "SkGradientShader.h"
+static sk_sp<SkShader> make_shader(const SkRect& r) {
+    const SkPoint pts[] = {
+        { r.fLeft, r.fTop }, { r.fRight, r.fBottom },
+    };
+    const SkColor colors[] = { 0, SK_ColorWHITE };
+    return SkGradientShader::MakeLinear(pts, colors, nullptr, 2, SkShader::kRepeat_TileMode);
+}
+
+DEF_SIMPLE_GM(shadermaskfilter_gradient, canvas, 512, 512) {
+    SkRect r = { 0, 0, 100, 150 };
+    auto shader = make_shader(r);
+    auto mf = SkShaderMaskFilter::Make(shader);
+
+    canvas->translate(20, 20);
+    canvas->scale(2, 2);
+
+    SkPaint paint;
+    paint.setMaskFilter(mf);
+    paint.setColor(SK_ColorRED);
+    canvas->drawOval(r, paint);
+}
+
+#include "Resources.h"
+DEF_SIMPLE_GM(shadermaskfilter_image, canvas, 512, 512) {
+    canvas->scale(1.25f, 1.25f);
+
+    auto image = GetResourceAsImage("images/mandrill_128.png");
+    auto mask = GetResourceAsImage("images/color_wheel.png");
+
+    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());
+}