Fixed rounding error in glyph size code that was truncating descenders.

Author: cmuratori

refterm_example_dwrite.cpp

@@ -14,14 +14,14 @@ extern "C" int D2DAcquire(IDXGISurface *GlyphTransferSurface,
                           struct ID2D1SolidColorBrush **DWriteFillBrush)
 {
     int Result = 0;
-    
+
     // TODO(casey): Obey "ClearType" here.
-    
+
     // TODO(casey): Not sure about these props...
     D2D1_RENDER_TARGET_PROPERTIES Props = D2D1::RenderTargetProperties(D2D1_RENDER_TARGET_TYPE_DEFAULT,
                                                                        D2D1::PixelFormat(DXGI_FORMAT_B8G8R8A8_UNORM, D2D1_ALPHA_MODE_PREMULTIPLIED),
                                                                        0, 0);
-    
+
     ID2D1Factory *Factory = 0;
     D2D1_FACTORY_OPTIONS Options = {};
     Options.debugLevel = D2D1_DEBUG_LEVEL_ERROR;
@@ -34,10 +34,10 @@ extern "C" int D2DAcquire(IDXGISurface *GlyphTransferSurface,
             (*DWriteRenderTarget)->CreateSolidColorBrush(D2D1::ColorF(1.0f, 1.0f, 1.0f, 1.0f), DWriteFillBrush);
             Result = (*DWriteFillBrush != 0);
         }
-        
+
         Factory->Release();
     }
-    
+
     return Result;
 }
 
@@ -49,7 +49,7 @@ extern "C" void D2DRelease(struct ID2D1RenderTarget **DWriteRenderTarget,
         (*DWriteFillBrush)->Release();
         *DWriteFillBrush = 0;
     }
-    
+
     if(*DWriteRenderTarget)
     {
         (*DWriteRenderTarget)->Release();
@@ -60,33 +60,35 @@ extern "C" void D2DRelease(struct ID2D1RenderTarget **DWriteRenderTarget,
 extern "C" int DWriteInit(glyph_generator *GlyphGen, IDXGISurface *GlyphTransferSurface)
 {
     int Result = 0;
-    
+
     DWriteCreateFactory(DWRITE_FACTORY_TYPE_SHARED, __uuidof(IDWriteFactory), (IUnknown**)&GlyphGen->DWriteFactory);
     if(GlyphGen->DWriteFactory)
     {
         Result = 1;
     }
-    
+
     return Result;
 }
 
 extern "C" SIZE DWriteGetTextExtent(glyph_generator *GlyphGen, int StringLen, wchar_t *String)
 {
     SIZE Result = {0};
-    
+
     IDWriteTextLayout *Layout = 0;
     GlyphGen->DWriteFactory->CreateTextLayout(String, StringLen, GlyphGen->TextFormat,
                                               (float)GlyphGen->TransferWidth, (float)GlyphGen->TransferHeight, &Layout);
     if(Layout)
     {
         DWRITE_TEXT_METRICS Metrics = {0};
         Layout->GetMetrics(&Metrics);
-        Result.cx = (uint32_t)Metrics.width;
-        Result.cy = (uint32_t)Metrics.height;
-        
+        Assert(Metrics.left == 0);
+        Assert(Metrics.top == 0);
+        Result.cx = (uint32_t)(Metrics.width + 0.5f);
+        Result.cy = (uint32_t)(Metrics.height + 0.5f);
+
         Layout->Release();
     }
-    
+
     return Result;
 }
 
@@ -97,14 +99,48 @@ void DWriteReleaseFont(glyph_generator *GlyphGen)
         GlyphGen->FontFace->Release();
         GlyphGen->FontFace = 0;
     }
+}
+
+void IncludeLetterBounds(glyph_generator *GlyphGen, wchar_t Letter)
+{
+    IDWriteTextLayout *Layout = 0;
+    GlyphGen->DWriteFactory->CreateTextLayout(&Letter, 1, GlyphGen->TextFormat,
+                                              (float)GlyphGen->TransferWidth, (float)GlyphGen->TransferHeight, &Layout);
+    if(Layout)
+    {
+        // TODO(casey): Real cell size determination would go here - probably with input from the user?
+        DWRITE_TEXT_METRICS CharMetrics = {0};
+        Layout->GetMetrics(&CharMetrics);
+
+        DWRITE_LINE_METRICS LineMetrics = {0};
+        UINT32 Ignored;
+        Layout->GetLineMetrics(&LineMetrics, 1, &Ignored);
+
+        if(GlyphGen->FontHeight < (uint32_t)(LineMetrics.height + 0.5f))
+        {
+            GlyphGen->FontHeight = (uint32_t)(LineMetrics.height + 0.5f);
+        }
+
+        if(GlyphGen->FontHeight < (uint32_t)(CharMetrics.height + 0.5f))
+        {
+            GlyphGen->FontHeight = (uint32_t)(CharMetrics.height + 0.5f);
+        }
+
+        if(GlyphGen->FontWidth < (uint32_t)(CharMetrics.width + 0.5f))
+        {
+            GlyphGen->FontWidth = (uint32_t)(CharMetrics.width + 0.5f);
+        }
+
+        Layout->Release();
     }
+}
 
 extern "C" int DWriteSetFont(glyph_generator *GlyphGen, wchar_t *FontName, uint32_t FontHeight)
 {
     int Result = 0;
-    
+
     DWriteReleaseFont(GlyphGen);
-    
+
     if(GlyphGen->DWriteFactory)
     {
         GlyphGen->DWriteFactory->CreateTextFormat(FontName,
@@ -119,31 +155,16 @@ extern "C" int DWriteSetFont(glyph_generator *GlyphGen, wchar_t *FontName, uint3
         {
             GlyphGen->TextFormat->SetParagraphAlignment(DWRITE_PARAGRAPH_ALIGNMENT_NEAR);
             GlyphGen->TextFormat->SetTextAlignment(DWRITE_TEXT_ALIGNMENT_LEADING);
-            
-            wchar_t M = L'M';
-            IDWriteTextLayout *Layout = 0;
-            GlyphGen->DWriteFactory->CreateTextLayout(&M, 1, GlyphGen->TextFormat,
-                                                      (float)GlyphGen->TransferWidth, (float)GlyphGen->TransferHeight, &Layout);
-            if(Layout)
-            {
-                // TODO(casey): Real cell size determination would go here - probably with input from the user?
-                DWRITE_TEXT_METRICS CharMetrics = {0};
-                Layout->GetMetrics(&CharMetrics);
-                
-                DWRITE_LINE_METRICS LineMetrics = {0};
-                UINT32 Ignored;
-                Layout->GetLineMetrics(&LineMetrics, 1, &Ignored);
-                
-                GlyphGen->FontHeight = (uint32_t)LineMetrics.height;
-                GlyphGen->FontWidth = (uint32_t)CharMetrics.width;
-                
-                Layout->Release();
-                
-                Result = 1;
-            }
+
+            GlyphGen->FontWidth = 0;
+            GlyphGen->FontHeight = 0;
+            IncludeLetterBounds(GlyphGen, L'M');
+            IncludeLetterBounds(GlyphGen, L'g');
+
+            Result = 1;
         }
     }
-    
+
     return Result;
 }
 
@@ -154,7 +175,7 @@ extern "C" void DWriteDrawText(glyph_generator *GlyphGen, int StringLen, WCHAR *
                                float XScale, float YScale)
 {
     D2D1_RECT_F Rect;
-    
+
     Rect.left = (float)Left;
     Rect.top = (float)Top;
     Rect.right = (float)Right;
@@ -176,12 +197,12 @@ extern "C" void DWriteDrawText(glyph_generator *GlyphGen, int StringLen, WCHAR *
 extern "C" void DWriteRelease(glyph_generator *GlyphGen)
 {
     /* NOTE(casey): There is literally no point to this function
-       whatsoever except to stop the D3D debug runtime from 
+       whatsoever except to stop the D3D debug runtime from
        complaining about unreleased resources when the program
        exits.  EVEN THOUGH THEY WOULD BE AUTOMATICALLY RELEASED
        AT THAT TIME.  So now here I am manually releasing them,
        which wastes the user's time, for no reason at all. */
-    
+
     DWriteReleaseFont(GlyphGen);
     if(GlyphGen->DWriteFactory) GlyphGen->DWriteFactory->Release();
 }