gfxlib2: force 96 dpi scaling on windows 7 to fix an issue with high dpi modes - no change for windows 10

Author: jayrm

changelog.txt

@@ -13,6 +13,7 @@ Version 1.09.0
 - fbc: gen gcc: allow compiling with GCC 4.5 and older, by avoiding -Wno-unused-but-set-variable (TeeEmCee)
 - fbc: internal function fbcQueryGcc() to ask gcc for the correct as & ld to use (TeeEmCee)
 - rtlib: freebsd: minimum thread stacksize 8192 KiB
+- gfxlib2: force 96 dpi scaling on windows 7 to fix an issue with high dpi modes - no change for windows 10
 
 [added]
 - fbc: add '-z fbrt' command line option to link against libfbrt*.a instead of libfb*.a

src/gfxlib2/win32/gfx_driver_d2d.c

@@ -13,6 +13,7 @@
 #include <d2d1.h>
 #include <dxgi.h>
 #include <stdlib.h>
+#include "VersionHelpers.h"
 
 /* Defining DEBUG or D2D_DEBUG will turn on debugging for Direct2D & Direct3D
 // (if it's used). To see any output from them you'll need to install 
@@ -193,6 +194,7 @@ typedef struct D2DGlobalState
 			ID2D1HwndRenderTarget* pHwndTarget; /* The guy that lets us render to a window */
 		} NonLayered;
 	} RenderParams;
+	BOOL isWin10;
 } D2DGlobalState;
 
 /* We could statically allocate the state as a global, but that would
@@ -234,6 +236,7 @@ static D2DGlobalState* CreateGlobalState(HWND hwnd, HMODULE hD2D, ID2D1Factory*
 			}
 			++i;
 		}
+		pState->isWin10 = IsWindows10OrGreater();
 		if(!SetProp(hwnd, MAKEINTRESOURCE(D2D_PROP_ID), (HANDLE)pState)) {
 			free(pState);
 			pState = NULL;
@@ -622,8 +625,20 @@ static void D2DCommonPaintInternal(D2DGlobalState* pGlobalState)
 	dirtyRect.bottom = ((pLastDirtyRow - pDirtyStart) + 1) * scanlineSize;
 	drawRect.left = dirtyRect.left;
 	drawRect.right = dirtyRect.right;
-	drawRect.top = dirtyRect.top;
-	drawRect.bottom = dirtyRect.bottom;
+
+	if( pGlobalState->isWin10 ) {
+		drawRect.top = dirtyRect.top;
+		drawRect.bottom = dirtyRect.bottom;
+	}
+	else {
+		/* on win7 the update / scaling doesn't work correctly.
+		// Only thing that seems to work at this point is if
+		// we update the entire window. (jeffm)
+		*/
+		drawRect.top = 0;
+		drawRect.bottom = winHeight;
+	}
+
 
 	DBG_TEXT("%s - dirty rect L-%lu, T-%lu, R-%lu, B-%lu", dirtyRect.left, dirtyRect.top, dirtyRect.right, dirtyRect.bottom);
 
@@ -640,6 +655,14 @@ static void D2DCommonPaintInternal(D2DGlobalState* pGlobalState)
 
 	ID2D1Bitmap_CopyFromMemory(pBackBuffer, &dirtyRect, pBitmapDataSrc, stride);
 
+	if( !pGlobalState->isWin10 )
+	{
+		/* win7 seems to handle ID2D1RenderTarget_DrawBitmap() differently
+		// than on win10.  Force the DPI for the render target otherwise
+		// we get weird scaling when system is in a high-dpi mode (jeffm).
+		*/
+		ID2D1RenderTarget_SetDpi( pRT, 96, 96 );
+	}
 	ID2D1RenderTarget_BeginDraw(pRT);
 	ID2D1RenderTarget_DrawBitmap(pRT, pBackBuffer, &drawRect, 1.0f, D2D1_BITMAP_INTERPOLATION_MODE_LINEAR, &drawRect);
 	if(pGlobalState->Paint)