use Mode struct for windows display code

src/display.c

@@ -47,7 +47,7 @@ typedef struct {
 static PyTypeObject ImagingDisplayType;
 
 static ImagingDisplayObject *
-_new(const char *mode, int xsize, int ysize) {
+_new(const Mode * const mode, int xsize, int ysize) {
     ImagingDisplayObject *display;
 
     if (PyType_Ready(&ImagingDisplayType) < 0) {
@@ -240,7 +240,7 @@ static struct PyMethodDef methods[] = {
 
 static PyObject *
 _getattr_mode(ImagingDisplayObject *self, void *closure) {
-    return Py_BuildValue("s", self->dib->mode);
+    return Py_BuildValue("s", self->dib->mode->name);
 }
 
 static PyObject *
@@ -288,13 +288,14 @@ static PyTypeObject ImagingDisplayType = {
 PyObject *
 PyImaging_DisplayWin32(PyObject *self, PyObject *args) {
     ImagingDisplayObject *display;
-    char *mode;
+    char *mode_name;
     int xsize, ysize;
 
-    if (!PyArg_ParseTuple(args, "s(ii)", &mode, &xsize, &ysize)) {
+    if (!PyArg_ParseTuple(args, "s(ii)", &mode_name, &xsize, &ysize)) {
         return NULL;
     }
 
+    const Mode * const mode = findMode(mode_name);
     display = _new(mode, xsize, ysize);
     if (display == NULL) {
         return NULL;
@@ -305,12 +306,9 @@ PyImaging_DisplayWin32(PyObject *self, PyObject *args) {
 
 PyObject *
 PyImaging_DisplayModeWin32(PyObject *self, PyObject *args) {
-    char *mode;
     int size[2];
-
+    const Mode * const mode = ImagingGetModeDIB(size);
-    mode = ImagingGetModeDIB(size);
+    return Py_BuildValue("s(ii)", mode->name, size[0], size[1]);
-
-    return Py_BuildValue("s(ii)", mode, size[0], size[1]);
 }
 
 /* -------------------------------------------------------------------- */

src/libImaging/Dib.c

@@ -25,20 +25,17 @@
 
 #include "ImDib.h"
 
-char *
+const Mode *
 ImagingGetModeDIB(int size_out[2]) {
     /* Get device characteristics */
 
-    HDC dc;
+    const HDC dc = CreateCompatibleDC(NULL);
-    char *mode;
 
-    dc = CreateCompatibleDC(NULL);
+    const Mode *mode = IMAGING_MODE_P;
-
-    mode = "P";
     if (!(GetDeviceCaps(dc, RASTERCAPS) & RC_PALETTE)) {
-        mode = "RGB";
+        mode = IMAGING_MODE_RGB;
         if (GetDeviceCaps(dc, BITSPIXEL) == 1) {
-            mode = "1";
+            mode = IMAGING_MODE_1;
         }
     }
 
@@ -53,7 +50,7 @@ ImagingGetModeDIB(int size_out[2]) {
 }
 
 ImagingDIB
-ImagingNewDIB(const char *mode, int xsize, int ysize) {
+ImagingNewDIB(const Mode * const mode, int xsize, int ysize) {
     /* Create a Windows bitmap */
 
     ImagingDIB dib;
@@ -61,10 +58,12 @@ ImagingNewDIB(const char *mode, int xsize, int ysize) {
     int i;
 
     /* Check mode */
-    if (strcmp(mode, "1") != 0 && strcmp(mode, "L") != 0 && strcmp(mode, "RGB") != 0) {
+    if (mode != IMAGING_MODE_1 && mode != IMAGING_MODE_L && mode != IMAGING_MODE_RGB) {
         return (ImagingDIB)ImagingError_ModeError();
     }
 
+    const int pixelsize = mode == IMAGING_MODE_RGB ? 3 : 1;
+
     /* Create DIB context and info header */
     /* malloc check ok, small constant allocation */
     dib = (ImagingDIB)malloc(sizeof(*dib));
@@ -83,7 +82,7 @@ ImagingNewDIB(const char *mode, int xsize, int ysize) {
     dib->info->bmiHeader.biWidth = xsize;
     dib->info->bmiHeader.biHeight = ysize;
     dib->info->bmiHeader.biPlanes = 1;
-    dib->info->bmiHeader.biBitCount = strlen(mode) * 8;
+    dib->info->bmiHeader.biBitCount = pixelsize * 8;
     dib->info->bmiHeader.biCompression = BI_RGB;
 
     /* Create DIB */
@@ -103,12 +102,12 @@ ImagingNewDIB(const char *mode, int xsize, int ysize) {
         return (ImagingDIB)ImagingError_MemoryError();
     }
 
-    strcpy(dib->mode, mode);
+    dib->mode = mode;
     dib->xsize = xsize;
     dib->ysize = ysize;
 
-    dib->pixelsize = strlen(mode);
+    dib->pixelsize = pixelsize;
-    dib->linesize = (xsize * dib->pixelsize + 3) & -4;
+    dib->linesize = (xsize * pixelsize + 3) & -4;
 
     if (dib->pixelsize == 1) {
         dib->pack = dib->unpack = (ImagingShuffler)memcpy;
@@ -132,7 +131,7 @@ ImagingNewDIB(const char *mode, int xsize, int ysize) {
     }
 
     /* Create an associated palette (for 8-bit displays only) */
-    if (strcmp(ImagingGetModeDIB(NULL), "P") == 0) {
+    if (ImagingGetModeDIB(NULL) == IMAGING_MODE_P) {
         char palbuf[sizeof(LOGPALETTE) + 256 * sizeof(PALETTEENTRY)];
         LPLOGPALETTE pal = (LPLOGPALETTE)palbuf;
         int i, r, g, b;
@@ -142,7 +141,7 @@ ImagingNewDIB(const char *mode, int xsize, int ysize) {
         pal->palNumEntries = 256;
         GetSystemPaletteEntries(dib->dc, 0, 256, pal->palPalEntry);
 
-        if (strcmp(mode, "L") == 0) {
+        if (mode == IMAGING_MODE_L) {
             /* Grayscale DIB.  Fill all 236 slots with a grayscale ramp
              * (this is usually overkill on Windows since VGA only offers
              * 6 bits grayscale resolution).  Ignore the slots already
@@ -156,8 +155,7 @@ ImagingNewDIB(const char *mode, int xsize, int ysize) {
             }
 
             dib->palette = CreatePalette(pal);
-
+        } else if (mode == IMAGING_MODE_RGB) {
-        } else if (strcmp(mode, "RGB") == 0) {
 #ifdef CUBE216
 
             /* Colour DIB.  Create a 6x6x6 colour cube (216 entries) and

src/libImaging/ImDib.h

@@ -27,7 +27,7 @@ struct ImagingDIBInstance {
     UINT8 *bits;
     HPALETTE palette;
     /* Used by cut and paste */
-    char mode[4];
+    const Mode *mode;
     int xsize, ysize;
     int pixelsize;
     int linesize;
@@ -37,11 +37,11 @@ struct ImagingDIBInstance {
 
 typedef struct ImagingDIBInstance *ImagingDIB;
 
-extern char *
+extern const Mode *
 ImagingGetModeDIB(int size_out[2]);
 
 extern ImagingDIB
-ImagingNewDIB(const char *mode, int xsize, int ysize);
+ImagingNewDIB(const Mode * const mode, int xsize, int ysize);
 
 extern void
 ImagingDeleteDIB(ImagingDIB im);