Smallest possible desktop application that uses Skia to render stuff.

experimental/SkiaExamples/HelloSkiaExample.cpp

+/*
+ * Copyright 2013 Google Inc.
+ *
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ *
+ */
+
+#include "HelloSkiaExample.h"
+
+#include "SkApplication.h"
+#include "SkDraw.h"
+#include "SkGradientShader.h"
+#include "SkGraphics.h"
+#include "SkUnitMappers.h"
+
+SkOSWindow* create_sk_window(void* hwnd, int argc, char** argv) {
+    return new HelloSkia(hwnd, argc, argv);
+}
+
+HelloSkia::HelloSkia(void* hWnd, int argc, char** argv)
+    : INHERITED(hWnd, argc, argv)
+{
+    fBGColor = SK_ColorWHITE;
+    fRotationAngle = SkIntToScalar(0);
+
+    setupBackend(kGPU_DeviceType);
+}
+
+void HelloSkia::draw(SkCanvas* canvas) {
+    // Clear background
+    canvas->drawColor(fBGColor);
+
+    SkPaint paint;
+    paint.setColor(SK_ColorRED);  // SkColor is ARGB
+
+    // Draw a rectangle with blue paint
+    SkRect rect = {SkIntToScalar(10), SkIntToScalar(10), SkIntToScalar(128), SkIntToScalar(128)};
+    canvas->drawRect(rect, paint);
+
+    // Set up a linear gradient and draw a circle
+    {
+        SkPoint linearPoints[] = {
+            {SkIntToScalar(0), SkIntToScalar(0)}, {SkIntToScalar(300), SkIntToScalar(300)}};
+        SkColor linearColors[] = {SK_ColorGREEN, SK_ColorBLACK};
+
+        SkUnitMapper* linearMapper = new SkDiscreteMapper(100);
+        SkAutoUnref lm_deleter(linearMapper);
+
+        SkShader* shader = SkGradientShader::CreateLinear(
+                linearPoints, linearColors, NULL, 2, SkShader::kMirror_TileMode, linearMapper);
+        SkAutoUnref shader_deleter(shader);
+
+        paint.setShader(shader);
+        paint.setFlags(SkPaint::kAntiAlias_Flag);
+
+        canvas->drawCircle(SkIntToScalar(200), SkIntToScalar(200), SkIntToScalar(64), paint);
+
+        // Detach shader
+        paint.setShader(NULL);
+    }
+
+
+    // Draw a message with a nice black paint.
+    paint.setFlags(
+            SkPaint::kAntiAlias_Flag |
+            SkPaint::kSubpixelText_Flag |  // ... avoid waggly text when rotating.
+            SkPaint::kUnderlineText_Flag);
+    paint.setColor(SK_ColorBLACK);
+    paint.setTextSize(SkIntToScalar(20));
+
+    canvas->save();
+
+    static const char message[] = "Hello Skia!!!";
+
+    // Translate and rotate
+    canvas->translate(SkIntToScalar(300), SkIntToScalar(300));
+    fRotationAngle += SkDoubleToScalar(0.2);
+    if (fRotationAngle > SkDoubleToScalar(360.0)) {
+        fRotationAngle -= SkDoubleToScalar(360.0);
+    }
+    canvas->rotate(fRotationAngle);
+
+    // Draw the text:
+    canvas->drawText(message, strlen(message), SkIntToScalar(0), SkIntToScalar(0), paint);
+
+    canvas->restore();
+
+    // Invalidate the window to force a redraw. Poor man's animation mechanism.
+    this->inval(NULL);
+    canvas->flush();
+
+    INHERITED::draw(canvas);
+}
+