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minetest-mapper-cpp
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Inform the user of libgd and system limitations when applicable. 

This is necessary, because libgd may fail, or print some
unintelligible message when these limits are reached.

Known limitations:
- libgd refuses to create images larger than approx INT_MAX (2^31-1)
  pixels (a little over 46300x46300), even on 64-bit systems.
- on a 32-bit system, in practise, the largest size that can be
  generated is a little over 24100x24100 pixels.
master
Rogier 2014-04-10 00:56:49 +02:00
parent c1f2df705b
commit 62f004ae0a
1 changed files with 15 additions and 0 deletions
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15
TileGenerator.cpp
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@ -603,6 +603,21 @@ void TileGenerator::createImage()
pictHeight += (tileBorderZLimit - tileBorderZStart) * m_tileBorderSize;
}
// Print some useful messages in cases where it may not be possible to generate the image...
long long pixels = static_cast<long long>(pictWidth + m_border) * (pictHeight + m_border);
// Study the libgd code to known why the maximum is the following:
long long max_pixels = INT_MAX - INT_MAX % pictHeight;
if (pixels > max_pixels) {
cerr << "WARNING: Image will have " << pixels << " pixels; the PNG graphics library will refuse to handle more than approximately " << INT_MAX << std::endl;
}
// Estimated approximate maximum was determined by trial and error...
// (24100x24100 succeeded; 24200x24200 failed)
#define ESTIMATED_MAX_PIXELS_32BIT (24100*24100L)
else if (sizeof(void *) == 4 && pixels > ESTIMATED_MAX_PIXELS_32BIT) {
cerr << "WARNING: Image will have " << pixels << " pixels; The maximum achievable on a 32-bit system is approximately " << ESTIMATED_MAX_PIXELS_32BIT << std::endl;
}
#undef ESTIMATED_MAX_PIXELS_32BIT
m_image = gdImageCreateTrueColor(pictWidth + m_border, pictHeight + m_border);
if (!m_image) {
ostringstream oss;