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 */
19extern "C"
20JNIEXPORT 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