我正在嘗試使用NDK在全屏上顯示位圖。 該要求迫使我使用完全本機代碼進行開發。 我使用Skia繪制SkBitmap ，然後通過Opengl APIs将其顯示。 當我的應用程式首次在真正的android裝置上運作時，它始終可以正常運作。 但是，在我多次打開和關閉程式之後，它将顯示出不好的圖像。 為什麼會這樣？
功能engine_init_display用于初始化OpenGL ES和EGL，建立位圖并加載紋理。
static int engine_init_display(struct engine* engine){
// initialize OpenGL ES and EGL
const EGLint attribs[] = {
EGL_SURFACE_TYPE, EGL_WINDOW_BIT,
EGL_DEPTH_SIZE, 16,
EGL_BLUE_SIZE, 8,
EGL_GREEN_SIZE, 8,
EGL_RED_SIZE, 8,
EGL_NONE
};
EGLint w, h, dummy, format;
EGLint numConfigs;
EGLConfig config;
EGLSurface surface;
EGLContext context;
EGLDisplay display = eglGetDisplay(EGL_DEFAULT_DISPLAY);
eglInitialize(display, 0, 0);
eglChooseConfig(display, attribs, &config, 1, &numConfigs);
eglGetConfigAttrib(display, config, EGL_NATIVE_VISUAL_ID, &format);
ANativeWindow_setBuffersGeometry(engine->app->window, 0, 0, format);
surface = eglCreateWindowSurface(display, config, engine->app->window, NULL);
context = eglCreateContext(display, config, NULL, NULL);
if (eglMakeCurrent(display, surface, surface, context) == EGL_FALSE) {
LOGW("Unable to eglMakeCurrent");
return -1;
}
eglQuerySurface(display, surface, EGL_WIDTH, &w);
eglQuerySurface(display, surface, EGL_HEIGHT, &h);
engine->display = display;
engine->context = context;
engine->surface = surface;
engine->width = w;
engine->height = h;
engine->state.angle = 0;
engine->format=format;
// Initialize GL state.
glHint(GL_PERSPECTIVE_CORRECTION_HINT, GL_FASTEST);
glEnable(GL_CULL_FACE);
glShadeModel(GL_SMOOTH);
glDisable(GL_DEPTH_TEST);
SkBitmap bitmap;
GLvoid* bitmapBuffer;
createBitmap(bitmap,bitmapBuffer,width,height);
drawBitmap(bitmap,width,height);
glEnable(GL_TEXTURE_2D);
glGenTextures(1,&sTexture);
glBindTexture(GL_TEXTURE_2D,sTexture);
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, width, height, 0, GL_RGBA, GL_UNSIGNED_BYTE, (GLvoid*)bitmapBuffer);
glDisable(GL_TEXTURE_2D);
glFinish();
clearBitmapBuffer(bitmap,bitmapBuffer);
//engine_draw_frame(engine);
return 0;
}
功能render是顯示位圖
void render(struct engine* engine, int width, int height){
glViewport((engine->width-width)/2, (engine->height-height)/2, width, height);
glClearColorx((GLfixed)(0.1f * 65536),(GLfixed)(0.2f * 65536),(GLfixed)(0.3f * 65536), 0x10000);
glClear(GL_COLOR_BUFFER_BIT);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
glMatrixMode(GL_TEXTURE);
glLoadIdentity();
glEnable(GL_TEXTURE_2D);
glTexParameterx(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexParameterx(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
glEnableClientState(GL_VERTEX_ARRAY);
glEnableClientState(GL_TEXTURE_COORD_ARRAY);
glBindTexture(GL_TEXTURE_2D,sTexture);
glFrontFace(GL_CW);
glTexCoordPointer(2, GL_FLOAT, 0, textureCoords);
glVertexPointer(3, GL_FLOAT, 0, vertices);
glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);
glDisable(GL_TEXTURE_2D);
glDisableClientState(GL_VERTEX_ARRAY);
glDisableClientState(GL_TEXTURE_COORD_ARRAY);
glFlush();
eglSwapBuffers(engine->display, engine->surface);
}
當視窗關閉時，将調用engine_term_display
static void engine_term_display(struct engine* engine) {
if (engine->display != EGL_NO_DISPLAY) {
eglMakeCurrent(engine->display, EGL_NO_SURFACE, EGL_NO_SURFACE, EGL_NO_CONTEXT);
if (engine->context != EGL_NO_CONTEXT) {
eglDestroyContext(engine->display, engine->context);
}
if (engine->surface != EGL_NO_SURFACE) {
eglDestroySurface(engine->display, engine->surface);
}
eglTerminate(engine->display);
}
engine->display = EGL_NO_DISPLAY;
engine->context = EGL_NO_CONTEXT;
engine->surface = EGL_NO_SURFACE;
}
更新
android_main是本機應用程式的主要入口點。 我發現當此主要功能傳回時，整個應用程式仍在運作。
void android_main(struct android_app* state) {
struct engine engine;
// Make sure glue isn't stripped.
app_dummy();
memset(&engine, 0, sizeof(engine));
state->userData = &engine;
state->onAppCmd = engine_handle_cmd;
state->onInputEvent = engine_handle_input;
engine.app = state;
ANativeActivity_setWindowFlags(engine.app->activity, AWINDOW_FLAG_FULLSCREEN, 0);
if (state->savedState != NULL) {
// We are starting with a previous saved state; restore from it.
engine.state = *(struct saved_state*)state->savedState;
}
while(1){
int ident;
int events;
struct android_poll_source* source;
if((ident=ALooper_pollAll(-1, NULL, &events,(void**)&source))>=0){
// Process this event.
if (source != NULL) {
source->process(state, source);
}
if (state->destroyRequested != 0) {
engine_term_display(&engine);
return;
}
}
}
}