mirrors/fltk
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

Windows: fix compiler warning [-Wstrict-aliasing]

Browse Source 
In function ‘void innards(...)’:
src/drivers/GDI/Fl_GDI_Graphics_Driver_image.cxx:132:23:
dereferencing type-punned pointer will break strict-aliasing rules
  BITMAPINFO &bmi = *((BITMAPINFO*)bmibuffer);
                     ~^~~~~~~~~~~~~~~~~~~~~~~

Found with gcc 12 (MinGW cross compiler)

Also: use correct sizes (sizeof) rather than hardcoded values.
This commit is contained in:
Albrecht Schlosser 2024-10-31 18:38:50 +01:00
parent bdb5972504
commit 34f465add2
1 changed files with 22 additions and 21 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

43
src/drivers/GDI/Fl_GDI_Graphics_Driver_image.cxx
View File

@ -1,7 +1,7 @@
//
// Windows image drawing code for the Fast Light Tool Kit (FLTK).
//
// Copyright 1998-2020 by Bill Spitzak and others.
// Copyright 1998-2024 by Bill Spitzak and others.
//
// This library is free software. Distribution and use rights are outlined in
// the file "COPYING" which should have been included with this file. If this
@ -128,43 +128,44 @@ static void innards(const uchar *buf, int X, int Y, int W, int H,
if (w<=0 || h<=0) return;
if (buf) buf += (x-X)*delta + (y-Y)*linedelta;
static U32 bmibuffer[256+12];
BITMAPINFO &bmi = *((BITMAPINFO*)bmibuffer);
if (!bmi.bmiHeader.biSize) {
bmi.bmiHeader.biSize = sizeof(bmi)-4; // does it use this to determine type?
bmi.bmiHeader.biPlanes = 1;
bmi.bmiHeader.biCompression = BI_RGB;
bmi.bmiHeader.biXPelsPerMeter = 0;
bmi.bmiHeader.biYPelsPerMeter = 0;
bmi.bmiHeader.biClrUsed = 0;
bmi.bmiHeader.biClrImportant = 0;
// bmibuffer: BITMAPINFOHEADER + 256 colors (RGBQUAD) + 1 (rounding effects ?)
static U32 bmibuffer[sizeof(BITMAPINFOHEADER)/4 + 257];
BITMAPINFO *bmi = (BITMAPINFO*)bmibuffer;
if (!bmi->bmiHeader.biSize) {
bmi->bmiHeader.biSize = sizeof(BITMAPINFOHEADER);
bmi->bmiHeader.biPlanes = 1;
bmi->bmiHeader.biCompression = BI_RGB;
bmi->bmiHeader.biXPelsPerMeter = 0;
bmi->bmiHeader.biYPelsPerMeter = 0;
bmi->bmiHeader.biClrUsed = 0;
bmi->bmiHeader.biClrImportant = 0;
}
#if USE_COLORMAP
if (indexed) {
for (short i=0; i<256; i++) {
*((short*)(bmi.bmiColors)+i) = i;
*((short*)(bmi->bmiColors)+i) = i;
}
} else
#endif
if (depth<3) {
RGBQUAD *bmi_colors = &bmi.bmiColors[0]; // suppress warning (STR #3199)
RGBQUAD *bmi_colors = &(bmi->bmiColors[0]); // use pointer to suppress warning (STR #3199)
for (int i=0; i<256; i++) {
bmi_colors[i].rgbBlue = (uchar)i; // bmi.bmiColors[i]...
bmi_colors[i].rgbBlue = (uchar)i; // = bmi->bmiColors[i]
bmi_colors[i].rgbGreen = (uchar)i;
bmi_colors[i].rgbRed = (uchar)i;
bmi_colors[i].rgbReserved = (uchar)0; // must be zero
}
}
bmi.bmiHeader.biWidth = w;
bmi->bmiHeader.biWidth = w;
#if USE_COLORMAP
bmi.bmiHeader.biBitCount = indexed ? 8 : depth*8;
bmi->bmiHeader.biBitCount = indexed ? 8 : depth*8;
int pixelsize = indexed ? 1 : depth;
#else
bmi.bmiHeader.biBitCount = depth*8;
bmi->bmiHeader.biBitCount = depth*8;
int pixelsize = depth;
#endif
if (depth==2) { // special case: gray with alpha
bmi.bmiHeader.biBitCount = 32;
bmi->bmiHeader.biBitCount = 32;
pixelsize = 4;
}
int linesize = (pixelsize*w+3)&~3;
@ -185,7 +186,7 @@ static void innards(const uchar *buf, int X, int Y, int W, int H,
buffer = new U32[(size + 3) / 4];
}
}
bmi.bmiHeader.biHeight = blocking;
bmi->bmiHeader.biHeight = blocking;
static U32* line_buffer;
if (!buf) {
int size = W*delta;
@ -259,7 +260,7 @@ static void innards(const uchar *buf, int X, int Y, int W, int H,
// does not do the expected job, whereas StretchDIBits does it.
StretchDIBits(gc, x, y+j-k, w, k, 0, 0, w, k,
(LPSTR)((uchar*)buffer+(blocking-k)*linesize),
&bmi,
bmi,
#if USE_COLORMAP
indexed ? DIB_PAL_COLORS : DIB_RGB_COLORS
#else
@ -273,7 +274,7 @@ static void innards(const uchar *buf, int X, int Y, int W, int H,
else {
SetDIBitsToDevice(gc, x, y+j-k, w, k, 0, 0, 0, k,
(LPSTR)((uchar*)buffer+(blocking-k)*linesize),
&bmi,
bmi,
#if USE_COLORMAP
indexed ? DIB_PAL_COLORS : DIB_RGB_COLORS
#else