add GDCAP_DPI for GetGDCapability

RELEASE-NOTES.md

@@ -11,6 +11,11 @@ Please report any bugs and incompatibilities in
 ### What's new in this version
 
 * ENHANCEMENTS:
+  1. Add a new key `dpi` for NEWGAL engine to define the DPI of the screen. 
+     If it is absent, use 96 as the default DPI.
+  1. Add an item for `GetGDCapability` to return DPI of the DC.
+  1. New API `InitSlaveScreenEx` to specify the DPI of slave screen. 
+     Define `InitSlaveScreen` as an inline function calling `InitSlaveScreenEx`.
   1. New API: `SyncUpdateDC`. You can use this function to synchronize 
     the update rectangles of a surface to screen, if the surface
     represents the shadow frame buffer of the screen. 

etc/MiniGUI.cfg

@@ -28,10 +28,10 @@ mtype=IMPS2
 
 [fbcon]
 defaultmode=1024x768-16bpp
-
-[qvfb]
-defaultmode=640x480-16bpp
-display=0
+# The resolution of the display
+# It is defined in dots (physical pixels) per inch
+# The default value is 96.
+dpi=96
 
 #{{ifdef _MGGAL_PCXVFB
 [pc_xvfb]

include/gdi.h

@@ -1138,6 +1138,9 @@ MG_EXPORT BOOL GUIAPI InitPolygonRegion (PCLIPRGN dst,
 #define GDCAP_BMASK         10
 #define GDCAP_AMASK         11
 #define GDCAP_PITCH         12
+#define GDCAP_DPI           13
+    #define GDCAP_DPI_DEFAULT   96
+    #define GDCAP_DPI_MINIMAL   36
 
 /**
  * \fn unsigned int GUIAPI GetGDCapability (HDC hdc, int iItem)
@@ -1181,6 +1184,8 @@ MG_EXPORT BOOL GUIAPI InitPolygonRegion (PCLIPRGN dst,
  *    Tell \a GetGDCapability to return the pixel alpha color mask for the DC.
  *  - GDCAP_PITCH\n
  *    Tell \a GetGDCapability to return the pitch (the bytes of one scan line) of the DC.
+ *  - GDCAP_DPI\n
+ *    Tell \a GetGDCapability to return the DPI (the dots per inch) of the DC.
  *
  * \return The capbility.
  */
@@ -7635,7 +7640,7 @@ MG_EXPORT BOOL GUIAPI mlsGetSlaveScreenInfo (HDC dc_mls, DWORD mask, int* offset
  *
  * This function is used to enable or diable a MLShadow slave screen. 
  * After creating a slave screen by  \a InitSlaveScreen successfully, its
- * default status is diabled. 
+ * default status is disabled. 
  *
  * \param dc_mls The handle of MLShadow slave screen.
  * \param enable Whether to enable the MLShadow slave screen.
@@ -7650,7 +7655,7 @@ MG_EXPORT BOOL GUIAPI mlsEnableSlaveScreen (HDC dc_mls, BOOL enable);
 #define ERR_BMP_UNKNOWN_TYPE    -2
 #define ERR_BMP_CANT_READ       -3
 #define ERR_BMP_CANT_SAVE       -4
-#define ERR_BMP_NOT_SUPPORTED   -5   
+#define ERR_BMP_NOT_SUPPORTED   -5
 #define ERR_BMP_MEM             -6
 #define ERR_BMP_LOAD            -7
 #define ERR_BMP_FILEIO          -8
@@ -7977,15 +7982,31 @@ MG_EXPORT BOOL GUIAPI InitBitmap (HDC hdc, Uint32 w, Uint32 h, Uint32 pitch,
                 BYTE* bits, PBITMAP bmp);
 
 /**
- * \fn HDC GUIAPI InitSlaveScreen (const char* name, const char* mode)
+ * \fn HDC GUIAPI InitSlaveScreenEx (const char* name, const char* mode, int dpi)
  * \brief Initializes slave screen.
- * 
+ *
  * \param name The gal engine name.
  * \param mode The display mode. For example : 640x480-16bpp. 
+ * \param dpi  The resolution of screen, should be a value larger than GDCAP_DPI_MINIMAL (36).
+ *
  * \return Valid handle on success, HDC_INVALID on failure. 
  *
  */
-MG_EXPORT HDC GUIAPI InitSlaveScreen (const char* name, const char* mode);
+MG_EXPORT HDC GUIAPI InitSlaveScreenEx (const char* name, const char* mode, int dpi);
+
+/**
+ * \fn HDC GUIAPI InitSlaveScreen (const char* name, const char* mode)
+ * \brief Initializes slave screen.
+ *
+ * \param name The gal engine name.
+ * \param mode The display mode. For example : 640x480-16bpp.
+ *
+ * \return Valid handle on success, HDC_INVALID on failure.
+ */
+inline HDC InitSlaveScreen (const char* name, const char* mode)
+{
+    return InitSlaveScreenEx(name, mode, GDCAP_DPI_DEFAULT);
+}
 
 /**
  * \fn void TerminateSlaveScreen (HDC hdc)

src/include/newgal.h

@@ -103,6 +103,7 @@ typedef struct GAL_Surface {
     int w, h;                           /* Read-only */
     /* VW[2018-01-18]: For 64b, use signed int instead of Uint32 for pitch. */
     int pitch;                          /* Read-only */
+    int dpi;                            /* Read-only */
     void *pixels;                       /* Read-write */
     int offset;                         /* Private */
 
@@ -191,7 +192,8 @@ extern int GAL_VideoInit (const char *driver_name, Uint32 flags);
 extern void GAL_VideoQuit (void);
 
 extern void gal_SlaveVideoQuit (GAL_Surface * surface);
-extern GAL_Surface *gal_SlaveVideoInit(const char* driver_name, const char* mode);
+extern GAL_Surface *gal_SlaveVideoInit(const char* driver_name,
+        const char* mode, int dpi);
 
 /* This function fills the given character buffer with the name of the
  * video driver, and returns a pointer to it if the video driver has

src/newgal/newgal.c

@@ -147,6 +147,11 @@ int mg_InitGAL (void)
     }
 #endif
 
+    if (GetMgEtcIntValue (engine, "dpi", &__gal_screen->dpi) < 0)
+        __gal_screen->dpi = GDCAP_DPI_DEFAULT;
+    else if (__gal_screen->dpi < GDCAP_DPI_MINIMAL)
+        __gal_screen->dpi = GDCAP_DPI_MINIMAL;
+
     for (i = 0; i < 17; i++) {
         SysPixelIndex [i] = GAL_MapRGB (__gal_screen->format, 
                         SysPixelColor [i].r, 

src/newgal/surface.c

@@ -121,6 +121,8 @@ GAL_Surface * GAL_CreateRGBSurface (Uint32 flags,
     surface->pitch = GAL_CalculatePitch(surface);
     surface->pixels = NULL;
     surface->offset = 0;
+    // for off-screen surface, DPI always be the default value
+    surface->dpi = GDCAP_DPI_DEFAULT;
     surface->hwdata = NULL;
     surface->map = NULL;
     surface->format_version = 0;

src/newgal/video.c

@@ -1283,7 +1283,7 @@ static GAL_Surface * Slave_SetVideoMode (GAL_VideoDevice *device,
     return surface;
 }
 
-GAL_Surface *gal_SlaveVideoInit(const char* driver_name, const char* mode)
+GAL_Surface *gal_SlaveVideoInit(const char* driver_name, const char* mode, int dpi)
 {
     GAL_Surface* surface; 
     GAL_VideoDevice *video;
@@ -1326,6 +1326,12 @@ GAL_Surface *gal_SlaveVideoInit(const char* driver_name, const char* mode)
         _DBG_PRINTF ("NEWGAL: Set video mode failure.\n");
         return NULL;
     }
+
+    if (dpi < GDCAP_DPI_MINIMAL)
+        surface->dpi = GDCAP_DPI_MINIMAL;
+    else
+        surface->dpi = dpi;
+
     return surface;
 }
 

src/newgdi/gdi.c

@@ -402,6 +402,10 @@ unsigned int GUIAPI GetGDCapability (HDC hdc, int iItem)
         case GDCAP_MAXY:
             iret = RECTH (pdc->DevRC) - 1;
             break;
+
+        case GDCAP_DPI:
+            iret = pdc->surface->dpi;
+            break;
     }
 
     UNLOCK(&__mg_gdilock);
@@ -3369,7 +3373,7 @@ void GUIAPI DeleteMemDC (HDC hdc)
     free (pmem_dc);
 }
 
-HDC GUIAPI InitSlaveScreen (const char* name, const char* mode)
+HDC GUIAPI InitSlaveScreenEx (const char* name, const char* mode, int dpi)
 {
     PDC pmem_dc = NULL;
     GAL_Surface* surface = NULL;
@@ -3378,7 +3382,7 @@ HDC GUIAPI InitSlaveScreen (const char* name, const char* mode)
     if (!(pmem_dc = malloc (sizeof(DC))))
         return HDC_INVALID;
 
-    if ((surface = gal_SlaveVideoInit(name, mode))) {
+    if ((surface = gal_SlaveVideoInit(name, mode, dpi))) {
         dc_InitScreenDC (pmem_dc, surface); 
         return (HDC)pmem_dc;
     }