将IWICBtmap写入文件 - 分辨率不正确

时间：2015-02-01 18:10:24

标签： c++ image winapi direct2d wic

我在下面的代码中读取图像（JPG用于测试），指定剪切矩形区域并写入＆＃34;剪切＆＃34;区域到文件。

我的测试图像是320 x 240像素@ 300dpi。当我在所有迹象中读到它时说它是那么大，但是当我把它写出来时，结果图像是102 x 76并且查看文件属性我看不到H / V分辨率。

现在320/102 = 3.1372和300/96 = 3.125所以屏幕分辨率与图像有什么关系吗？

写出IWICBitmap的整个主题从一开始就是拳击比赛。为什么这么难？

非常感谢

IWICImagingFactory *pImageFactory = GfxAgent::WICImagingFactory::GetInstance().GetFactory();

   D2D1_SIZE_U sizeFrame = D2D1::SizeU(imageRect.Width(), imageRect.Height());

   CComPtr<IWICBitmap> pWICBitmap;
   hr = pImageFactory->CreateBitmap(imageRect.Width(), imageRect.Height(),
      GUID_WICPixelFormat32bppPBGRA,
      WICBitmapCacheOnLoad,
      &pWICBitmap
      );

   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;

   // define the render target
   CComPtr<ID2D1RenderTarget> pRenderTarget = 0;
   hr = m_pDirect2dFactory->CreateWicBitmapRenderTarget(pWICBitmap, rtProps, &pRenderTarget);

   CComPtr<ID2D1Bitmap> imageS;
   hr = GfxAgent::ImageUtilities::LoadImageFromFile(pRenderTarget, m_imgPath, 0, 0, 0, &imageS, &resX, &resY);

   if (hr != S_OK)
   {
   }

   // get format of image we just read
   D2D1_PIXEL_FORMAT fmt = imageS->GetPixelFormat();

   CComPtr<ID2D1Bitmap> imageD;
   D2D1_SIZE_U bitmapPixelSize = D2D1::SizeU(imageRect.Width(), imageRect.Height());

   // create destination image of "clipped" source image
   hr = pRenderTarget->CreateBitmap(bitmapPixelSize, D2D1::BitmapProperties(
      D2D1::PixelFormat(fmt.format, fmt.alphaMode),
      (float)resX, (float)resY), &imageD);

   D2D1_POINT_2U topleft = D2D1::Point2U(0, 0);
   D2D1_RECT_U srcRect = D2D1::RectU(imageRect.left, imageRect.top, imageRect.right, imageRect.bottom);
   // get the "clipped" source
   hr = imageD->CopyFromBitmap(&topleft, imageS, &srcRect);

   if (hr != S_OK)
   {
   }

   CComPtr<IWICBitmapEncoder> pEncoder;
   CComPtr<IWICBitmapFrameEncode> pFrame;
   CComPtr<IWICStream> pStream;

   WICPixelFormatGUID format = GUID_WICPixelFormat32bppPBGRA;

   // draw the "clipped" image into the render target (WIC image)
   if (SUCCEEDED(hr)) {
      pRenderTarget->BeginDraw();
      pRenderTarget->Clear();
      pRenderTarget->DrawBitmap(imageD);
      hr = pRenderTarget->EndDraw();
   }

   // now proceed to write the "clipped" image to a file
   if (SUCCEEDED(hr)) {
      hr = pImageFactory->CreateStream(&pStream);
   }

   if (SUCCEEDED(hr)) {
      hr = pStream->InitializeFromFilename(MultiByteToUnicode(szNewFileName).c_str(), GENERIC_WRITE);
   }

   if (SUCCEEDED(hr)) {
      hr = pImageFactory->CreateEncoder(GUID_ContainerFormatJpeg, NULL, &pEncoder);
   }

   if (SUCCEEDED(hr)) {
      hr = pEncoder->Initialize(pStream, WICBitmapEncoderNoCache);
   }

   if (SUCCEEDED(hr)) {
      hr = pEncoder->CreateNewFrame(&pFrame, NULL);
   }

   if (SUCCEEDED(hr)) {
      hr = pFrame->Initialize(NULL);
   }

   if (SUCCEEDED(hr)) {
      hr = pFrame->SetSize((UINT)imageD->GetSize().width, (UINT)imageD->GetSize().height);
   }

   if (SUCCEEDED(hr)) {
      hr = pFrame->SetPixelFormat(&format);
   }

   if (SUCCEEDED(hr)) {
      hr = pFrame->WriteSource(pWICBitmap, NULL);
   }

   if (SUCCEEDED(hr)) {
      hr = pFrame->Commit();
   }

   if (SUCCEEDED(hr)) {
      hr = pEncoder->Commit();
   }

更多信息

      D2D1_POINT_2U topleft = D2D1::Point2U(0, 0);
   D2D1_RECT_U srcRect = D2D1::RectU(imageRect.left, imageRect.top, imageRect.right, imageRect.bottom);
   // get the "clipped" source
   hr = imageD->CopyFromBitmap(&topleft, imageS, &srcRect);

   if (hr != S_OK)
   {
   }

   UINT wD, hD;
   wD = (UINT)imageD->GetSize().width;
   hD = (UINT)imageD->GetSize().height;

imageRect是正确的LTRB = 0,0,320,240

但复制后wD = 102且hD = 76

为什么？

以下是更多信息

CComPtr<ID2D1Bitmap> imageD;
   D2D1_SIZE_U bitmapPixelSize = D2D1::SizeU(imageRect.Width(), imageRect.Height());

   // create destination image of "clipped" source image
   hr = pRenderTarget->CreateBitmap(bitmapPixelSize, D2D1::BitmapProperties(
      D2D1::PixelFormat(fmt.format, fmt.alphaMode),
      (float)resX, (float)resY), &imageD);

   UINT wD, hD;
   wD = (UINT)imageD->GetSize().width;
   hD = (UINT)imageD->GetSize().height;

bitmapPixelSize是正确的320 x 240，resX和Y是300 

    format= DXGI_FORMAT_B8G8R8A8_UNORM
    alphaMode   D2D1_ALPHA_MODE_PREMULTIPLIED

wD = 102且hD = 76 - 为什么？

最新代码

IWICImagingFactory *pImageFactory = GfxAgent::WICImagingFactory::GetInstance().GetFactory();

   D2D1_SIZE_U sizeFrame = D2D1::SizeU(imageRect.Width(), imageRect.Height());

   CComPtr<IWICBitmap> pWICBitmap;
   hr = pImageFactory->CreateBitmap(imageRect.Width(), imageRect.Height(),
      GUID_WICPixelFormat32bppPBGRA,
      WICBitmapCacheOnLoad,
      &pWICBitmap
      );

   // sanity check
   UINT wicW, wicH;
   pWICBitmap->GetSize(&wicW, &wicH);

   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;

   // define the render target
   CComPtr<ID2D1RenderTarget> pRenderTarget = 0;
   hr = m_pDirect2dFactory->CreateWicBitmapRenderTarget(pWICBitmap, rtProps, &pRenderTarget);

   CComPtr<ID2D1Bitmap> imageS;
   hr = GfxAgent::ImageUtilities::LoadImageFromFile(pRenderTarget, m_imgPath, 0, 0, 0, &imageS, &resX, &resY);

   if (hr != S_OK)
   {
   }

   // set new image resolution same as source
   pWICBitmap->SetResolution(resX, resY);

   // get format of image we just read
   D2D1_PIXEL_FORMAT fmt = imageS->GetPixelFormat();

   CComPtr<ID2D1Bitmap> imageD;
   D2D1_SIZE_U bitmapPixelSize = D2D1::SizeU(imageRect.Width(), imageRect.Height());

   // create destination image of "clipped" source image
   hr = pRenderTarget->CreateBitmap(bitmapPixelSize, D2D1::BitmapProperties(
      D2D1::PixelFormat(fmt.format, fmt.alphaMode),
      (float)resX, (float)resY), &imageD);

   D2D1_POINT_2U topleft = D2D1::Point2U(0, 0);
   D2D1_RECT_U srcRect = D2D1::RectU(imageRect.left, imageRect.top, imageRect.right, imageRect.bottom);
   // get the "clipped" source
   hr = imageD->CopyFromBitmap(&topleft, imageS, &srcRect);

   if (hr != S_OK)
   {
   }

   // just a sanity check (pixels NOT DIPS)
   D2D1_SIZE_U sourcePixelSize = imageS->GetPixelSize();
   D2D1_SIZE_U destPixelSize = imageD->GetPixelSize();

   CComPtr<IWICBitmapEncoder> pEncoder;
   CComPtr<IWICBitmapFrameEncode> pFrame;
   CComPtr<IWICStream> pStream;

   WICPixelFormatGUID format = GUID_WICPixelFormat32bppPBGRA;

   // draw the "clipped" image into the render target (WIC image)
   if (SUCCEEDED(hr)) {
      pRenderTarget->BeginDraw();
      pRenderTarget->Clear();
      pRenderTarget->DrawBitmap(imageD);
      hr = pRenderTarget->EndDraw();
   }

   // now proceed to write the "clipped" image to a file
   if (SUCCEEDED(hr)) {
      hr = pImageFactory->CreateStream(&pStream);
   }

   if (SUCCEEDED(hr)) {
      hr = pStream->InitializeFromFilename(MultiByteToUnicode(szNewFileName).c_str(), GENERIC_WRITE);
   }

   if (SUCCEEDED(hr)) {
      hr = pImageFactory->CreateEncoder(GUID_ContainerFormatJpeg, NULL, &pEncoder);
   }

   if (SUCCEEDED(hr)) {
      hr = pEncoder->Initialize(pStream, WICBitmapEncoderNoCache);
   }

   if (SUCCEEDED(hr)) {
      hr = pEncoder->CreateNewFrame(&pFrame, NULL);
   }

   if (SUCCEEDED(hr)) {
      hr = pFrame->Initialize(NULL);
   }

   if (SUCCEEDED(hr)) {
      hr = pFrame->SetSize(destPixelSize.width, destPixelSize.height);
   }

   if (SUCCEEDED(hr)) {
      hr = pFrame->SetPixelFormat(&format);
   }

   if (SUCCEEDED(hr)) {
      hr = pFrame->WriteSource(pWICBitmap, NULL);
   }

   if (SUCCEEDED(hr)) {
      hr = pFrame->Commit();
   }

   if (SUCCEEDED(hr)) {
      hr = pEncoder->Commit();
   }

2 个答案:

答案 0 :(得分：1)

ID2D1Bitmap::GetSize为您提供DIP：

  

返回位图的与设备无关的像素（DIP）的大小。

     

DIP是1/96英寸。要检索设备像素的大小，请使用ID2D1Bitmap :: GetPixelSize方法。

在您的情况下，尺寸为320 px * 96 dpi / px / 300 dpi = 102.4与设备无关的像素。沿Y轴相同。

答案 1 :(得分：0)

当我从WICBitmap创建渲染目标时，知道原始图像的分辨率是什么我使用了以下属性

   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;
   rtProps.dpiX = (float)m_img.GetResolutionX();
   rtProps.dpiY = (float)m_img.GetResolutionY();

关键是在创建时使用原始图像的分辨率，试图在以后设置它们什么也没做。罗马给了我“提示” - 谢谢

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