include/core/GP_Context.h

   1 /*****************************************************************************
   2  * This file is part of gfxprim library.                                     *
   3  *                                                                           *
   4  * Gfxprim is free software; you can redistribute it and/or                  *
   5  * modify it under the terms of the GNU Lesser General Public                *
   6  * License as published by the Free Software Foundation; either              *
   7  * version 2.1 of the License, or (at your option) any later version.        *
   8  *                                                                           *
   9  * Gfxprim is distributed in the hope that it will be useful,                *
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of            *
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU         *
  12  * Lesser General Public License for more details.                           *
  13  *                                                                           *
  14  * You should have received a copy of the GNU Lesser General Public          *
  15  * License along with gfxprim; if not, write to the Free Software            *
  16  * Foundation, Inc., 51 Franklin Street, Fifth Floor,                        *
  17  * Boston, MA  02110-1301  USA                                               *
  18  *                                                                           *
  19  * Copyright (C) 2009-2011 Jiri "BlueBear" Dluhos                            *
  20  *                         <jiri.bluebear.dluhos@gmail.com>                  *
  21  *                                                                           *
  22  * Copyright (C) 2009-2012 Cyril Hrubis <metan@ucw.cz>                       *
  23  *                                                                           *
  24  *****************************************************************************/
  25
  26 #ifndef CORE_GP_CONTEXT_H
  27 #define CORE_GP_CONTEXT_H
  28
  29 #include <stdint.h>
  30 #include <unistd.h>
  31
  32 #include "GP_Common.h"
  33 #include "GP_Types.h"
  34 #include "GP_Pixel.h"
  35
  36 /* This structure holds all information needed for drawing into an image. */
  37 typedef struct GP_Context {
  38         uint8_t *pixels;         /* pointer to image pixels */
  39         uint8_t bpp;             /* pixel length in bits */
  40         uint32_t bytes_per_row;
  41         uint32_t w;              /* width in pixels */
  42         uint32_t h;              /* height in pixels */
  43         /*
  44          * Row bit offset. The offset is ignored for byte aligned pixels.
  45          * Basically it's used for non aligned pixels with combination
  46          * with subcontextes.
  47          */
  48         uint8_t offset;
  49
  50         GP_PixelType pixel_type; /* hardware pixel format */
  51
  52         /* image orientation. Most common is landscape (0, 0, 0),
  53          * portrait with normal topleft corner is (1, 0, 0).
  54          */
  55         uint8_t axes_swap:1;    /* swap axes so that x is y and y is x */
  56         uint8_t x_swap:1;       /* swap direction on x  */
  57         uint8_t y_swap:1;       /* swap direction on y  */
  58         uint8_t bit_endian:1;   /* GP_BIT_ENDIAN */
  59         uint8_t free_pixels:1;  /* If set pixels are freed on GP_ContextFree */
  60 } GP_Context;
  61
  62 /* Determines the address of a pixel within the context's image.
  63  * Rows and columns are specified in the image's orientation
  64  * (i.e. they might not be XY if the image is rotated).
  65  */
  66 #define GP_PIXEL_ADDR(context, x, y) (((context)->pixels \
  67         + y * (context)->bytes_per_row \
  68         + (x * (context)->bpp) / 8))
  69
  70 #define GP_CALC_ROW_SIZE(pixel_type, width) \
  71          ((GP_PixelSize(pixel_type) * width) / 8 + \
  72         !!((GP_PixelSize(pixel_type) * width) % 8))
  73
  74 /* Performs a series of sanity checks on context, aborting if any fails. */
  75 #define GP_CHECK_CONTEXT(context) do { \
  76         GP_CHECK(context, "NULL passed as context"); \
  77         GP_CHECK(context->pixels, "invalid context: NULL image pointer"); \
  78         GP_CHECK(context->bpp <= 32, "invalid context: unsupported bits-per-pixel count"); \
  79         GP_CHECK(context->w > 0 && context->h > 0, "invalid context: invalid image size"); \
  80 } while (0)
  81
  82 /*
  83  * Is true, when pixel is clipped out of context.
  84  */
  85 #define GP_PIXEL_IS_CLIPPED(context, x, y) \
  86         ((x) < 0 || x >= (typeof(x)) context->w \
  87         || (y) < 0 || y >= (typeof(y)) context->h) \
  88
  89 /*
  90  * Check for exactly same rotation flags.
  91  */
  92 #define GP_CONTEXT_ROTATION_EQUAL(c1, c2) \
  93         ((c1)->axes_swap == (c2)->axes_swap && \
  94          (c1)->x_swap    == (c2)->x_swap && \
  95          (c1)->y_swap    == (c2)->y_swap)
  96
  97 /*
  98  * Allocate context.
  99  */
 100 GP_Context *GP_ContextAlloc(GP_Size w, GP_Size h, GP_PixelType type);
 101
 102 /*
 103  * Initalize context, pixels pointer is not dereferenced so it's safe to pass
 104  * NULL there and allocate it later with size context->bpr * context->h.
 105  */
 106 void GP_ContextInit(GP_Context *context, GP_Size w, GP_Size h,
 107                     GP_PixelType type, void *pixels);
 108
 109 /*
 110  * Resizes context->pixels array and changes metadata to match.
 111  *
 112  * Returns non-zero on failure (remalloc() has failed).
 113  */
 114 int GP_ContextResize(GP_Context *context, GP_Size w, GP_Size h);
 115
 116 /*
 117  * If passed the pixels are copied to newly created context, otherwise
 118  * the pixels are allocated but uninitalized.
 119  */
 120 #define GP_COPY_WITH_PIXELS 1
 121
 122 /*
 123  * Copy context.
 124  */
 125 GP_Context *GP_ContextCopy(const GP_Context *src, int flag);
 126
 127 /*
 128  * Create subcontext.
 129  *
 130  * If pointer to subcontext is NULL, new context is allocated
 131  * otherwise context pointed by subcontext pointer is initalized.
 132  *
 133  * The free_pixels flag is set to 0 upon subcontext initalization so the
 134  * GP_ContextFree() would not call free() upon the subcontext->pixels pointer.
 135  */
 136 GP_Context *GP_ContextSubContext(GP_Context *context, GP_Context *subcontext,
 137                                  GP_Coord x, GP_Coord y, GP_Size w, GP_Size h);
 138
 139 /*
 140  * Converts context to a different pixel type.
 141  * Returns a newly allocated context.
 142  *
 143  * This is naive implementation that doesn't do any ditherings or error
 144  * diffusions.
 145  */
 146 GP_Context *GP_ContextConvert(const GP_Context *src,
 147                               GP_PixelType dst_pixel_type);
 148
 149 /*
 150  * Free context.
 151  *
 152  * If context->free_pixels, also free pixel data.
 153  */
 154 void GP_ContextFree(GP_Context *context);
 155
 156 /*
 157  * Rotates context flags clock wise.
 158  */
 159 void GP_ContextFlagsRotateCW(GP_Context *context);
 160
 161 /*
 162  * Rotates context flags counter clock wise.
 163  */
 164 void GP_ContextFlagsRotateCCW(GP_Context *context);
 165
 166 /*
 167  * Returns context width and height taking the rotation flags into a account.
 168  */
 169 static inline GP_Size GP_ContextW(const GP_Context *context)
 170 {
 171         if (context->axes_swap)
 172                 return context->h;
 173         else
 174                 return context->w;
 175 }
 176
 177 static inline GP_Size GP_ContextH(const GP_Context *context)
 178 {
 179         if (context->axes_swap)
 180                 return context->w;
 181         else
 182                 return context->h;
 183 }
 184
 185 #endif /* CORE_GP_CONTEXT_H */