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) 2009-2010 Jiri "BlueBear" Dluhos                            *
  20  *                         <jiri.bluebear.dluhos@gmail.com>                  *
  21  *                                                                           *
  22  * Copyright (C) 2009-2010 Cyril Hrubis <metan@ucw.cz>                       *
  23  *                                                                           *
  24  *****************************************************************************/
  25
  26 #ifndef GP_CONTEXT_H
  27 #define GP_CONTEXT_H
  28
  29 #include <stdint.h>
  30 #include <unistd.h>
  31
  32 #include "GP_Common.h"
  33 #include "GP_Pixel.h"
  34
  35 /* This structure holds all information needed for drawing into an image. */
  36 typedef struct GP_Context {
  37         uint8_t *pixels;         /* pointer to image pixels */
  38         uint8_t bpp;             /* values: 1, 2, 4, 8, 16, 24, 32 */
  39         uint32_t bytes_per_row;
  40         uint32_t w;              /* width */
  41         uint32_t h;              /* height */
  42
  43         GP_PixelType pixel_type; /* hardware pixel format */
  44
  45         /* image orientation. Most common is landscape (0, 0, 0),
  46          * portrait with normal topleft corner is (1, 0, 0).
  47          */
  48         int axes_swap:1;         /* swap axes so that x is y and y is x */
  49         int x_swap:1;            /* swap direction on x  */
  50         int y_swap:1;            /* swap direction on y  */
  51
  52         /* clipping rectangle; drawing functions only affect the inside */
  53         uint32_t clip_w_min;
  54         uint32_t clip_w_max;
  55         uint32_t clip_h_min;
  56         uint32_t clip_h_max;
  57 } GP_Context;
  58
  59 /* Returns the pixel type used by the context. */
  60 inline GP_PixelType GP_GetContextPixelType(const GP_Context *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, \
  77                                 "NULL passed as context"); \
  78                 GP_CHECK(context->pixels, \
  79                                 "invalid context: NULL image pointer"); \
  80                 GP_CHECK(context->bpp <= 32, \
  81                                 "invalid context: unsupported bits-per-pixel count"); \
  82                 GP_CHECK(context->w > 0 && context->h > 0, \
  83                                 "invalid context: invalid image size"); \
  84                 GP_CHECK(context->clip_w_min <= context->clip_w_max \
  85                                 && context->clip_h_min <= context->clip_h_max, \
  86                                 "invalid context: invalid clipping rectangle"); \
  87                 GP_CHECK(context->clip_w_max < context->w \
  88                                 && context->clip_h_max < context->h, \
  89                                 "invalid context: clipping rectangle larger than image"); \
  90         } while (0)
  91
  92 /*
  93  * Is true, when pixel is clipped.
  94  */
  95 #define GP_PIXEL_IS_CLIPPED(context, x, y) \
  96         (x < (int) context->clip_w_min \
  97         || x > (int) context->clip_w_max \
  98         || y < (int) context->clip_h_min \
  99         || y > (int) context->clip_h_max) \
 100
 101 /*
 102  * Allocate context.
 103  */
 104 GP_Context *GP_ContextAlloc(uint32_t w, uint32_t h, GP_PixelType type);
 105
 106 /*
 107  * If passed the pixels are copied to newly created context, otherwise
 108  * the pixels are allocated but uninitalized.
 109  */
 110 #define GP_COPY_WITH_PIXELS 1
 111
 112 /*
 113  * Copy context.
 114  */
 115 GP_Context *GP_ContextCopy(GP_Context *context, int flag);
 116
 117 /*
 118  * Free context.
 119  */
 120 void GP_ContextFree(GP_Context *context);
 121
 122 /*
 123  * Dump context into file
 124  */
 125 GP_RetCode GP_ContextDump(GP_Context *context, const char *path);
 126
 127 /*
 128  * Rotates context flags.
 129  */
 130 void GP_ContextFlagsRotateCW(GP_Context *context);
 131 void GP_ContextFlagsRotateCCW(GP_Context *context);
 132
 133 /*
 134  * Returns context width and height.
 135  */
 136 static inline uint32_t GP_ContextW(GP_Context *context)
 137 {
 138         return context->w;
 139 }
 140
 141 static inline uint32_t GP_ContextH(GP_Context *context)
 142 {
 143         return context->h;
 144 }
 145
 146 static inline uint32_t GP_TContextW(GP_Context *context)
 147 {
 148         if (context->axes_swap)
 149                 return context->h;
 150         else
 151                 return context->w;
 152 }
 153
 154 static inline uint32_t GP_TContextH(GP_Context *context)
 155 {
 156         if (context->axes_swap)
 157                 return context->w;
 158         else
 159                 return context->h;
 160 }
 161
 162 #endif /* GP_CONTEXT_H */