Remove FindSDL2 find-module, use sdl2-config.cmake instead
This requires SDL >= 2.0.4.
Since <https://bugzilla.libsdl.org/show_bug.cgi?id=2464> was fixed in
SDL 2.0.4, SDL behaves as a CMake "config-file package", even if it was
not itself built using CMake: it installs a sdl2-config.cmake file to
${libdir}/cmake/SDL2, which tells CMake where to find SDL's headers and
library, analogous to a pkg-config .pc file.
As a result, we no longer need to copy/paste a "find-module package"
to be able to find a system copy of SDL >= 2.0.4 with find_package(SDL2).
Find-module packages are now discouraged by the CMake developers, in
favour of having upstream projects behave as config-file packages.
This results in a small API change: FindSDL2 used to set SDL2_INCLUDE_DIR
and SDL2_LIBRARY, but the standard behaviour for config-file packages is
to set <name>_INCLUDE_DIRS and <name>_LIBRARIES. Use the CONFIG keyword
to make sure we search in config-file package mode, and will not find a
FindSDL2.cmake in some other directory that implements the old interface.
In addition to deleting redundant code, this avoids some assumptions in
FindSDL2 about the layout of a SDL installation. The current libsdl2-dev
package in Debian breaks those assumptions; this is considered a bug
and will hopefully be fixed soon, but it illustrates how fragile these
assumptions can be. We can be more robust against different installation
layouts by relying on SDL's own CMake integration.
When linking to a copy of CMake in a non-standard location, users can
now set the SDL2_DIR or CMAKE_PREFIX_PATH environment variable to point
to it; previously, these users would have used the SDL2DIR environment
variable. This continues to be unnecessary if using matching system-wide
installations of CMake and SDL2, for example both from Debian.
(*
* Hedgewars, a free turn based strategy game
* Copyright (c) 2004-2015 Andrey Korotaev <unC0Rr@gmail.com>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; version 2 of the License
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*)
{$INCLUDE "options.inc"}
unit PNGh;
interface
uses png;
{$IFDEF DARWIN}
{$linklib png}
{$ENDIF}
const
// Constants for libpng, they are not defined in png unit.
// We actually do not need all of them.
// These describe the color_type field in png_info.
// color type masks
PNG_COLOR_MASK_PALETTE = 1;
PNG_COLOR_MASK_COLOR = 2;
PNG_COLOR_MASK_ALPHA = 4;
// color types. Note that not all combinations are legal
PNG_COLOR_TYPE_GRAY = 0;
PNG_COLOR_TYPE_PALETTE = PNG_COLOR_MASK_COLOR or PNG_COLOR_MASK_PALETTE;
PNG_COLOR_TYPE_RGB = PNG_COLOR_MASK_COLOR;
PNG_COLOR_TYPE_RGB_ALPHA = PNG_COLOR_MASK_COLOR or PNG_COLOR_MASK_ALPHA;
PNG_COLOR_TYPE_GRAY_ALPHA = PNG_COLOR_MASK_ALPHA;
// aliases
PNG_COLOR_TYPE_RGBA = PNG_COLOR_TYPE_RGB_ALPHA;
PNG_COLOR_TYPE_GA = PNG_COLOR_TYPE_GRAY_ALPHA;
// This is for compression type. PNG 1.0-1.2 only define the single type.
PNG_COMPRESSION_TYPE_BASE = 0; // Deflate method 8, 32K window
PNG_COMPRESSION_TYPE_DEFAULT = PNG_COMPRESSION_TYPE_BASE;
// This is for filter type. PNG 1.0-1.2 only define the single type.
PNG_FILTER_TYPE_BASE = 0; // Single row per-byte filtering
PNG_INTRAPIXEL_DIFFERENCING = 64; // Used only in MNG datastreams
PNG_FILTER_TYPE_DEFAULT = PNG_FILTER_TYPE_BASE;
// These are for the interlacing type. These values should NOT be changed.
PNG_INTERLACE_NONE = 0; // Non-interlaced image
PNG_INTERLACE_ADAM7 = 1; // Adam7 interlacing
PNG_INTERLACE_LAST = 2; // Not a valid value
type
// where is better place for this definition?
PFile = ^file;
procedure png_init_pascal_io(png_ptr: png_structp; pf : PFile);
implementation
// We cannot get c-style FILE* pointer to pass it to libpng, so we implement our own writing functions
procedure PngWriteData(png_ptr: png_structp; p: PByte; len: png_size_t); cdecl;
begin
BlockWrite( PFile(png_get_io_ptr(png_ptr))^, p^, len);
end;
procedure PngFlushData(png_ptr: png_structp); cdecl;
begin
png_ptr:= png_ptr;
end;
procedure png_init_pascal_io(png_ptr: png_structp; pf : PFile);
begin
png_set_write_fn(png_ptr, pf, @PngWriteData, @PngFlushData);
end;
end.