Scale custom button image according to current DPI

Fixes #2246

Author: ge0rdi

Src/Lib/ResourceHelper.cpp

@@ -384,14 +384,14 @@ HICON CreateDisabledIcon( HICON hIcon, int iconSize )
 }
 
 // Loads an image file into a bitmap and optionally resizes it
-HBITMAP LoadImageFile( const wchar_t *path, const SIZE *pSize, bool bUseAlpha, bool bPremultiply, std::vector<unsigned int> *pButtonAnim )
+HBITMAP LoadImageFile( const wchar_t *path, const SIZE *pSize, bool bUseAlpha, bool bPremultiply, std::vector<unsigned int> *pButtonAnim, UINT dpi )
 {
 	HBITMAP srcBmp=NULL;
 	if (_wcsicmp(PathFindExtension(path),L".bmp")==0)
 	{
 		srcBmp=(HBITMAP)LoadImage(NULL,path,IMAGE_BITMAP,0,0,LR_CREATEDIBSECTION|LR_LOADFROMFILE);
 	}
-	if (srcBmp && !pSize)
+	if (srcBmp && !pSize && !dpi)
 		return srcBmp;
 	CComPtr<IWICImagingFactory> pFactory;
 	if (FAILED(pFactory.CoCreateInstance(CLSID_WICImagingFactory)))
@@ -482,6 +482,12 @@ HBITMAP LoadImageFile( const wchar_t *path, const SIZE *pSize, bool bUseAlpha, b
 			else
 				frameHeightD=frameWidthD*frameHeightS/frameWidthS;
 		}
+
+		if (dpi)
+		{
+			frameWidthD=ScaleForDpi(dpi,frameWidthD);
+			frameHeightD=ScaleForDpi(dpi,frameHeightD);
+		}
 	}
 
 	BITMAPINFO bi={0};
@@ -946,7 +952,12 @@ UINT GetDpi(HWND hwnd)
 	return dpi;
 }
 
+int ScaleForDpi(UINT dpi, int value)
+{
+	return MulDiv(value, dpi, USER_DEFAULT_SCREEN_DPI);
+}
+
 int ScaleForDpi(HWND hwnd, int value)
 {
-	return MulDiv(value, GetDpi(hwnd), USER_DEFAULT_SCREEN_DPI);
+	return ScaleForDpi(GetDpi(hwnd), value);
 }

Src/Lib/ResourceHelper.h

@@ -35,7 +35,7 @@ HICON ShExtractIcon( const char *path, int index, int iconSize );
 HBITMAP BitmapFromIcon( HICON hIcon, int iconSize, unsigned int **pBits, bool bDestroyIcon );
 
 // Loads an image file into a bitmap and optionally resizes it
-HBITMAP LoadImageFile( const wchar_t *path, const SIZE *pSize, bool bUseAlpha, bool bPremultiply, std::vector<unsigned int> *pButtonAnim );
+HBITMAP LoadImageFile( const wchar_t *path, const SIZE *pSize, bool bUseAlpha, bool bPremultiply, std::vector<unsigned int> *pButtonAnim, UINT dpi=0 );
 
 // Loads a bitmap from a IMAGE resource
 HBITMAP LoadImageResource( HMODULE hModule, const wchar_t *name, bool bTopDown, bool bPremultiply );
@@ -88,6 +88,8 @@ HFONT CreateFontSetting( const wchar_t *fontStr, int dpi );
 // Return DPI of given window (or system DPI on older systems)
 UINT GetDpi(HWND hwnd = nullptr);
 
+// Scale given value according to given DPI
+int ScaleForDpi(UINT dpi, int value);
 // Scale given value according to DPI of window
 int ScaleForDpi(HWND hwnd, int value);
 

Src/StartMenu/StartMenuDLL/StartButton.cpp

@@ -526,16 +526,16 @@ void CStartButton::LoadBitmap( void )
 	}
 	else
 	{
+		int dpi=GetDpi(GetParent());
 		bool bResource=false;
 		std::vector<unsigned int> buttonAnim;
 		if (*path)
 		{
-			m_Bitmap=LoadImageFile(path,&size,true,true,&buttonAnim);
+			m_Bitmap=LoadImageFile(path,&size,true,true,&buttonAnim,dpi);
 		}
 		if (!m_Bitmap)
 		{
 			int id;
-			int dpi=GetDpi(GetParent());
 			if (dpi<120)
 				id=IDB_BUTTON96;
 			else if (dpi<144)