android 直接在屏幕上绘图

android 的application 都是有窗口系统的，会把各种事件给阻拦掉．但是，用c++写的程序是直接在linux上运行的，并没有窗口这一概念，所以可以向鼠标一样，只绘制图像而不响应任何窗口时间.

具体实现是通过SurfaceComposerClient，这个类相当于surfaceflinger的代理，可以创建一个显示图像的surface. 

注意，不同系统的接口可能不一样．若有问题，可以参考一下本系统中frameworks/base/service/input/SpriteController.cpp中的doUpdateSprites()函数.这个函数是显示鼠标的最主核心的函数．

 1 #include<SkImageDecoder.h>
 2 #include <utils/RefBase.h>
 3 #include <utils/Looper.h>
 4 #include <gui/SurfaceComposerClient.h>
 5 #include <gui/Surface.h>
 6 #include <SkBitmap.h>
 7 #include <SkCanvas.h>
 8 #include <SkColor.h>
 9 #include <SkPaint.h>
10 #include <SkXfermode.h>
11 #include <android/native_window.h>
12 #include <unistd.h>
13 #include <cutils/log.h>
14 #include <ui/DisplayInfo.h>
15 
16 #define LOG_TAG "zhy"
17 
18 using namespace android;
19 int main()
20 {
21     SkBitmap bitmap;
22     SkImageDecoder::DecodeFile("/system/data/test.png", &bitmap);
23     sp<SurfaceComposerClient> pSurfaceComposerClient = new SurfaceComposerClient();
24     int32_t width = bitmap.height();
25     int32_t height = bitmap.width();
26     ALOGI("width= %d \n", width);
27     ALOGI("height= %d \n", height);
28     sp<SurfaceControl> surfaceControl = pSurfaceComposerClient->createSurface(
29         String8("test"), width, height, PIXEL_FORMAT_RGBA_8888,
30         ISurfaceComposerClient::eHidden);
31     
32     if (surfaceControl == NULL || !surfaceControl->isValid()) {
33         ALOGE("Error creating sprite surface.");
34         return -1;
35     }
36     sp<Surface> surface = surfaceControl->getSurface();
37     ANativeWindow_Buffer outBuffer;
38     status_t status = surface->lock(&outBuffer, NULL);
39     if (status) {
40                 ALOGE("Error %d locking sprite surface before drawing.", status);
41     } else {
42         SkBitmap surfaceBitmap;
43         ssize_t bpr = outBuffer.stride * bytesPerPixel(outBuffer.format);
44         surfaceBitmap.setConfig(SkBitmap::kARGB_8888_Config,
45                 outBuffer.width, outBuffer.height, bpr);
46         surfaceBitmap.setPixels(outBuffer.bits);
47         SkCanvas surfaceCanvas(surfaceBitmap);
48         SkPaint paint;
49         paint.setXfermodeMode(SkXfermode::kSrc_Mode);
50         surfaceCanvas.drawBitmap(bitmap, 0, 0, &paint);
51         if (outBuffer.width > uint32_t(bitmap.width())) {
52             paint.setColor(0); // transparent fill color
53             surfaceCanvas.drawRectCoords(bitmap.width(), 0,
54                     outBuffer.width, bitmap.height(), paint);
55         }
56         if (outBuffer.height > uint32_t(bitmap.height())) {
57             paint.setColor(0); // transparent fill color
58             surfaceCanvas.drawRectCoords(0, bitmap.height(),
59                     outBuffer.width, outBuffer.height, paint);
60         }
61         status = surface->unlockAndPost();
62         if (status) {
63             ALOGE("Error %d unlocking and posting sprite surface after drawing.", status);
64         }
65     }
66    
67     int x = 0, y = 0;
68     SurfaceComposerClient::openGlobalTransaction();
69     //surfaceControl->setAlpha(1.0f);
70     surfaceControl->setLayer(100000);
71     //surfaceControl->setMatrix(1.0, 1.0, 1.0, 1.0);
72     SurfaceComposerClient::closeGlobalTransaction();
73     while(true){
74         ALOGI("openGlobalTransaction \n");
75         SurfaceComposerClient::openGlobalTransaction();
76         surfaceControl->setPosition(x, y);
77         x = (x+10) %1920;
78         y = (y+10) %1280;
79              static bool isShow = false;
80              if(!isShow){
81                  surfaceControl->show();
82                  isShow = true;
83              }
84           ALOGI("closeGlobalTransaction \n");
85         SurfaceComposerClient::closeGlobalTransaction();
86            sleep(1);
87            
88     }
89     return 0;
90 }
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posted @ 2014-05-26 16:19  Jaunty_  阅读(1261)  评论(0)  编辑  收藏  举报