如何将ID2D1Bitmap保存到PNG文件 [英] How to save ID2D1Bitmap to PNG file

问题描述

我在尝试将ID2D1Bitmap（从ID2D1HwndRenderTarget创建）保存到PNG文件时遇到了问题。输出图像只是空白，带有白色。从函数调用EndDraw（）返回的HRESULT是-2003238894。

I faced a problem when trying to save ID2D1Bitmap (that created from ID2D1HwndRenderTarget) to PNG File. The output image is just empty with white color. HRESULT returned from function call EndDraw() is -2003238894.

感谢您的帮助。

这是我的代码：

HRESULT CImageUtil::SaveBitmapToFile(PCWSTR uri,ID2D1Bitmap* pBitmap,ID2D1RenderTarget* pRenderTarget)
{

HRESULT hr = S_OK;

ID2D1Factory *pD2DFactory = NULL;
IWICBitmap *pWICBitmap = NULL;
ID2D1RenderTarget *pRT = NULL;
IWICBitmapEncoder *pEncoder = NULL;
IWICBitmapFrameEncode *pFrameEncode = NULL;
IWICStream *pStream = NULL;

if (SUCCEEDED(hr))
{
    hr = D2D1CreateFactory(D2D1_FACTORY_TYPE_SINGLE_THREADED, &pD2DFactory);
}

//
// Create IWICBitmap and RT
//

UINT sc_bitmapWidth = pBitmap->GetSize().width;
UINT sc_bitmapHeight = pBitmap->GetSize().height;

if (SUCCEEDED(hr))
{
    hr = m_pWICFactory->CreateBitmap(
        sc_bitmapWidth,
        sc_bitmapHeight,
    GUID_WICPixelFormat32bppPBGRA,
        WICBitmapCacheOnLoad,
        &pWICBitmap
        );
}

if (SUCCEEDED(hr))
{
    D2D1_RENDER_TARGET_PROPERTIES rtProps = D2D1::RenderTargetProperties();
    rtProps.pixelFormat = D2D1::PixelFormat(DXGI_FORMAT_B8G8R8A8_UNORM, D2D1_ALPHA_MODE_PREMULTIPLIED);
    rtProps.type = D2D1_RENDER_TARGET_TYPE_DEFAULT;
    rtProps.usage = D2D1_RENDER_TARGET_USAGE_NONE;

    hr = pD2DFactory->CreateWicBitmapRenderTarget(
        pWICBitmap,
    rtProps,
        &pRT
        );
}

if (SUCCEEDED(hr))
{
    //
    // Render into the bitmap
    //
    pRT->BeginDraw();

pRT->Clear(D2D1::ColorF(D2D1::ColorF::White));


pRT->DrawBitmap(pBitmap);

    pRT->EndDraw();
}
if (SUCCEEDED(hr))
{

    //
    // Save image to file
    //
    hr = m_pWICFactory->CreateStream(&pStream);
}

WICPixelFormatGUID format = GUID_WICPixelFormat32bppPBGRA;
if (SUCCEEDED(hr))
{

    hr = pStream->InitializeFromFilename(uri, GENERIC_WRITE);
}
if (SUCCEEDED(hr))
{
    hr = m_pWICFactory->CreateEncoder(GUID_ContainerFormatPng, NULL, &pEncoder);
}
if (SUCCEEDED(hr))
{
    hr = pEncoder->Initialize(pStream, WICBitmapEncoderNoCache);
}
if (SUCCEEDED(hr))
{
    hr = pEncoder->CreateNewFrame(&pFrameEncode, NULL);
}
if (SUCCEEDED(hr))
{
    hr = pFrameEncode->Initialize(NULL);
}

if (SUCCEEDED(hr))
{
    hr = pFrameEncode->SetSize(sc_bitmapWidth, sc_bitmapHeight);
}
if (SUCCEEDED(hr))
{
    hr = pFrameEncode->SetPixelFormat(&format);
}
if (SUCCEEDED(hr))
{
    hr = pFrameEncode->WriteSource(pWICBitmap, NULL);
}
if (SUCCEEDED(hr))
{
    hr = pFrameEncode->Commit();
}
if (SUCCEEDED(hr))
{
    hr = pEncoder->Commit();
}

SafeRelease(&pD2DFactory);
SafeRelease(&pWICBitmap);
SafeRelease(&pRT);
SafeRelease(&pEncoder);
SafeRelease(&pFrameEncode);
SafeRelease(&pStream);

return hr;
}

推荐答案

你怎么知道你有一个错误，因为你只是吞下错误并继续而不是记录他们来自哪里？你得到一个非零的结果，所以首先通过在每个函数调用后添加printf或fprintf来确定它来自哪个函数。你在这个区块中有一个明显的遗漏：

How would you even know if you had an error, since you just swallow errors and continue instead of logging where they came from? You get a non-zero hresult, so first figure out which function it comes from by adding a printf or fprintf after every single function call. And you have a glaring omission in the block:

if (SUCCEEDED(hr))
{
    //
    // Render into the bitmap
    //
    pRT->BeginDraw();

pRT->Clear(D2D1::ColorF(D2D1::ColorF::White));


pRT->DrawBitmap(pBitmap);

    pRT->EndDraw();
}
if (SUCCEEDED(hr))

你不打扰在那里的任何地方分配hr，所以你甚至不知道它们中的任何一个是错误的。显然，Clear（）和最后的png写入工作正常，因为你得到了一个好文件，所以它是DrawBitmap或其中一个失败的位图创建调用。

You don't bother to assign hr anywhere in there, so you wouldn't even know if any of them are erroring out. Obviously, Clear() and the final png writing work fine, since you get a good file, so it's DrawBitmap or one of the bitmap creation calls that are failing.

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