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 "SkDraw.h"
+#include "SkGradientShader.h"
+#include "SkGraphics.h"
+#include "SkUnitMappers.h"
+
+// The following three methods need to be defined so that your example
+// runs on Linux and Mac.
+SkOSWindow* create_sk_window(void* hwnd, int argc, char** argv) {
+    return new HelloSkia(hwnd, argc, argv);
+}
+
+void application_init() {
+    SkGraphics::Init();
+    SkEvent::Init();
+}
+
+void application_term() {
+    SkEvent::Term();
+    SkGraphics::Term();
+}
+
+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 = {10, 10, 128, 128};

[caryclark, 2013/06/10 15:48:40]

these need SkIntToScalar functions

[sglez, 2013/06/11 04:24:38]

Thanks; did a regex substitution on the file.

+    canvas->drawRect(rect, paint);
+
+    // Set up a linear gradient and draw a circle
+    {
+        SkPoint linearPoints[] = {{0, 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(200, 200, 64, paint);

[caryclark, 2013/06/10 15:48:40]

SkIntToScalar

+
+        // 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(300, 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), 0, 0, paint);
+
+    canvas->restore();
+
+    // Invalidate the window to force a redraw. Poor man's animation mechanism.
+    this->inval(NULL);
+    canvas->flush();
+
+    if (getDeviceType() == kGPU_DeviceType) {

[caryclark, 2013/06/10 15:48:40]

since the base class does this, call it here

[sglez, 2013/06/11 04:24:38]

Done.

+        present();
+    }
+}
+