1 #include <math.h> 2 #include <jni.h> 3 #include <android/bitmap.h> 4 5 #include "SkCanvas.h" 6 #include "SkGraphics.h" 7 #include "SkSurface.h" 8 #include "SkString.h" 9 #include "SkTime.h" 10 11 12 /** 13 * Draws something into the given bitmap 14 * @param env 15 * @param thiz 16 * @param dstBitmap The bitmap to place the results of skia into 17 * @param elapsedTime The number of milliseconds since the app was started 18 */ 19 extern "C" 20 JNIEXPORT void JNICALL Java_com_example_HelloSkiaActivity_drawIntoBitmap(JNIEnv* env, 21 jobject thiz, jobject dstBitmap, jlong elapsedTime) 22 { 23 // Grab the dst bitmap info and pixels 24 AndroidBitmapInfo dstInfo; 25 void* dstPixels; 26 AndroidBitmap_getInfo(env, dstBitmap, &dstInfo); 27 AndroidBitmap_lockPixels(env, dstBitmap, &dstPixels); 28 29 SkImageInfo info = SkImageInfo::MakeN32Premul(dstInfo.width, dstInfo.height); 30 31 // Create a surface from the given bitmap 32 SkAutoTUnref<SkSurface> surface(SkSurface::NewRasterDirect(info, dstPixels, dstInfo.stride)); 33 SkCanvas* canvas = surface->getCanvas(); 34 35 // Draw something "interesting" 36 37 // Clear the canvas with a white color 38 canvas->drawColor(SK_ColorWHITE); 39 40 // Setup a SkPaint for drawing our text 41 SkPaint paint; 42 paint.setColor(SK_ColorBLACK); // This is a solid black color for our text 43 paint.setTextSize(SkIntToScalar(30)); // Sets the text size to 30 pixels 44 paint.setAntiAlias(true); // We turn on anti-aliasing so that the text to looks good. 45 46 // Draw some text 47 SkString text("Skia is Best!"); 48 SkScalar fontHeight = paint.getFontSpacing(); 49 canvas->drawText(text.c_str(), text.size(), // text's data and length 50 10, fontHeight, // X and Y coordinates to place the text 51 paint); // SkPaint to tell how to draw the text 52 53 // Adapt the SkPaint for drawing blue lines 54 paint.setAntiAlias(false); // Turning off anti-aliasing speeds up the line drawing 55 paint.setColor(0xFF0000FF); // This is a solid blue color for our lines 56 paint.setStrokeWidth(SkIntToScalar(2)); // This makes the lines have a thickness of 2 pixels 57 58 // Draw some interesting lines using trig functions 59 for (int i = 0; i < 100; i++) 60 { 61 float x = (float)i / 99.0f; 62 float offset = elapsedTime / 1000.0f; 63 canvas->drawLine(sin(x * M_PI + offset) * 800.0f, 0, // first endpoint 64 cos(x * M_PI + offset) * 800.0f, 800, // second endpoint 65 paint); // SkPapint to tell how to draw the line 66 } 67 68 // Unlock the dst's pixels 69 AndroidBitmap_unlockPixels(env, dstBitmap); 70 } 71
