Copybit调研报告2
Copybit模块在android2.0以后归OpenGL管理，在libagl中专门有一个copybit.cpp文件对其进一步封装并进行管理。
当然，也有越狱的时候，这个我们在后面讨论，首先还是看看copybit.cpp。
首先看android.mk,有个宏定义，默认是打开的
#define LIBAGL_USE_GRALLOC_COPYBITS
1、libagl/copybit.cpp
//检查是否有copybit
static bool checkContext(ogles_context_t* c)
//copybit进一步封装
static bool copybit(GLint x, GLint y,
GLint w, GLint h,
EGLTextureObject* textureObject,
const GLint* crop_rect,
int transform,
ogles_context_t* c)
简单工作流程：
1）将texture转换为copybit格式
textureToCopyBitImage(&textureObject->surface, opFormat,textureObject->buffer, &src);
2）如果有alpha值需要倒三次
copybit->stretch(copybit, &tmpCbImg, &dst, &tmpCbRect, &tmpdrect, &tmp_it);
copybit->stretch(copybit, &dst, &src, &drect, &srect, &it);
copybit->stretch(copybit, &dst, &tmpCbImg, &tmpdrect, &tmpCbRect, &it);
3）else如果没有alpha，只需要做一次
opybit->stretch(copybit, &dst, &src, &drect, &srect, &it);
//Try to draw a triangle fan with copybit画一个三角扇形，是对copybit函数的进一步封装，较复杂
bool drawTriangleFanWithCopybit_impl(ogles_context_t* c, GLint first, GLsizei count)
//Try to drawTexiOESWithCopybit copybit的简单封装
bool drawTexiOESWithCopybit_impl(GLint x, GLint y, GLint z, GLint w, GLint h, ogles_context_t* c)
2、libagl对copybit的调用
1）打开copybit模块
State.cpp
ogles_context_t *ogles_init(size_t extra)
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hw_get_module(COPYBIT_HARDWARE_MODULE_ID, &module)
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copybit_open(module, ©Bits)
c->copybits.blitEngine = copyBits;
2)操作copybit
Texture.cpp
void glDrawTexsvOES(const GLshort* coords)<----这个是API
void glDrawTexivOES(const GLint* coords)<----这个是API
void glDrawTexsOES(GLshort x , GLshort y, GLshort z, GLshort w, GLshort h)<----这个是API
void glDrawTexiOES(GLint x, GLint y, GLint z, GLint w, GLint h)<----这个是API
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drawTexiOES(x, y, z, w, h, c);
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drawTexiOESWithCopybit(x, y, z, w, h, c)
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drawTexiOESWithCopybit_impl(x, y, z, w, h, c)
void glDrawTexfvOES(const GLfloat* coords)<----这个是API
void glDrawTexxvOES(const GLfixed* coords)<----这个是API
void glDrawTexfOES(GLfloat x, GLfloat y, GLfloat z, GLfloat w, GLfloat h)<----这个是API
void glDrawTexxOES(GLfixed x, GLfixed y, GLfixed z, GLfixed w, GLfixed h)<----这个是API
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drawTexxOES(x, y, z, w, h, c);
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drawTexiOESWithCopybit(gglFixedToIntRound(x),
gglFixedToIntRound(y), gglFixedToIntRound(z),
gglFixedToIntRound(w), gglFixedToIntRound(h), c)
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drawTexiOESWithCopybit_impl(x, y, z, w, h, c);
void glEGLImageTargetTexture2DOES(GLenum target, GLeglImageOES image)
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tex->try_copybit = true;
Array.cpp
void glDrawArrays(GLenum mode, GLint first, GLsizei count) <----这个是API
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void drawPrimitivesTriangleFan(ogles_context_t* c, GLint first, GLsizei count) <----mode6
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drawTriangleFanWithCopybit(c, first, count)
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drawTriangleFanWithCopybit_impl(c, first, count)
3、copybit的越狱？
并不是所有代码都使用了封装好的copybit，也并不是仅有opengl能够使用copybit模块，看看下面的：
1）libagl/egl.cpp 有个copyBIt函数直接用了copybit的blit
void egl_window_surface_v2_t::copyBlt(
android_native_buffer_t* dst, void* dst_vaddr,
android_native_buffer_t* src, void const* src_vaddr,
const Region& clip)
{
// FIXME: use copybit if possible
// NOTE: dst and src must be the same format
status_t err = NO_ERROR;
copybit_device_t* const copybit = blitengine;
if (copybit) {
copybit_image_t simg;
simg.w = src->width;
simg.h = src->height;
simg.format = src->format;
simg.handle = const_cast(src->handle);
copybit_image_t dimg;
dimg.w = dst->width;
dimg.h = dst->height;
dimg.format = dst->format;
dimg.handle = const_cast(dst->handle);
copybit->set_parameter(copybit, COPYBIT_TRANSFORM, 0);
copybit->set_parameter(copybit, COPYBIT_PLANE_ALPHA, 255);
copybit->set_parameter(copybit, COPYBIT_DITHER, COPYBIT_DISABLE);
region_iterator it(clip);
err = copybit->blit(copybit, &dimg, &simg, &it);
if (err != NO_ERROR) {
LOGE("copybit failed (%s)", strerror(err));
}
}
//如果没有则是软件处理的
if (!copybit || err) {
Region::const_iterator cur = clip.begin();
Region::const_iterator end = clip.end();
const size_t bpp = pixelFormatTable[src->format].size;
const size_t dbpr = dst->stride * bpp;
const size_t sbpr = src->stride * bpp;
uint8_t const * const src_bits = (uint8_t const *)src_vaddr;
uint8_t * const dst_bits = (uint8_t *)dst_vaddr;
while (cur != end) {
const Rect& r(*cur++);
ssize_t w = r.right - r.left;
ssize_t h = r.bottom - r.top;
if (w <= 0 || h<=0) continue;
size_t size = w * bpp;
uint8_t const * s = src_bits + (r.left + src->stride * r.top) * bpp;
uint8_t * d = dst_bits + (r.left + dst->stride * r.top) * bpp;
if (dbpr==sbpr && size==sbpr) {
size *= h;
h = 1;
}
do {
memcpy(d, s, size);
d += dbpr;
s += sbpr;
} while (--h > 0);
}
}
}
2）frameworks\base\libs\surfaceflinger\Layerbuffer.cpp
很奇怪，这儿竟然也用了copybit
void LayerBuffer::onFirstRef()
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hw_get_module(COPYBIT_HARDWARE_MODULE_ID, &module)
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copybit_open(module, &mBlitEngine);
void LayerBuffer::BufferSource::onDraw(const Region& clip) const
...
#if defined(EGL_ANDROID_image_native_buffer)
if (mLayer.mFlags & DisplayHardware::DIRECT_TEXTURE) {
copybit_device_t* copybit = mLayer.mBlitEngine;
if (copybit) {
// create our EGLImageKHR the first time
err = initTempBuffer();
if (err == NO_ERROR) {
// NOTE: Assume the buffer is allocated with the proper USAGE flags
const NativeBuffer& dst(mTempBuffer);
region_iterator clip(Region(Rect(dst.crop.r, dst.crop.b)));
copybit->set_parameter(copybit, COPYBIT_TRANSFORM, 0);
copybit->set_parameter(copybit, COPYBIT_PLANE_ALPHA, 0xFF);
copybit->set_parameter(copybit, COPYBIT_DITHER, COPYBIT_ENABLE);
err = copybit->stretch(copybit, &dst.img, &src.img,
&dst.crop, &src.crop, &clip);
}
} else {
err = INVALID_OPERATION;
}
}
#endif
...
3）还有，比如高通的Gralloc模块里面也用到了copybit
总之，看了这枚多，先写一个copybit模块试试吧。
Rockie Cheng
