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 "BaseExample.h"

#include "SkApplication.h"
#include "SkDraw.h"
#include "SkGradientShader.h"
#include "SkGraphics.h"
#include "SkUnitMappers.h"

class HelloSkia : public BaseExample {
    public:
        HelloSkia(void* hWnd, int argc, char** argv)
            : INHERITED(hWnd, argc, argv)
        {
            fBGColor = SK_ColorWHITE;
            fRotationAngle = SkIntToScalar(0);

            setupBackend(kGPU_DeviceType);
            // Another option is software rendering:
            // setupBackend(kRaster_DeviceType);
        }

    protected:
        virtual void draw(SkCanvas* canvas) SK_OVERRIDE {
            // Clear background
            canvas->drawColor(fBGColor);

            SkPaint paint;
            paint.setColor(SK_ColorRED);

            // 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);

            INHERITED::draw(canvas);
        }

    private:
        SkScalar fRotationAngle;
        SkColor fBGColor;
        typedef BaseExample INHERITED;
};

SkOSWindow* create_sk_window(void* hwnd, int argc, char** argv) {
    return new HelloSkia(hwnd, argc, argv);
}