This patch adds bitmap scaling support to GRUB. It also adds support to gfxterm for scaling the background image to fit the screen. The background_image command supports a new -m/--mode option, which takes "stretch" (the default) or "normal" as values.
The patch is against GRUB trunk revision 1964. Vesa started a discussion about more flexible handling of bitmaps including the concept of optimizing loaded bitmaps into a display-specific format, at which point they could no longer be modified by functions like the bitmap scaling functions. This bitmap format optimization would be nice to add, but I think we can at least add this basic bitmap scaling functionality to start with. It only supports 24/32 bpp direct color modes at this point to keep things simple. Regards, Colin
=== modified file 'conf/common.rmk' --- conf/common.rmk 2009-01-13 16:34:26 +0000 +++ conf/common.rmk 2009-01-31 20:28:20 +0000 @@ -446,7 +446,7 @@ videotest_mod_LDFLAGS = $(COMMON_LDFLAGS) # For bitmap.mod -bitmap_mod_SOURCES = video/bitmap.c +bitmap_mod_SOURCES = video/bitmap.c video/bitmap_scale.c bitmap_mod_CFLAGS = $(COMMON_CFLAGS) bitmap_mod_LDFLAGS = $(COMMON_LDFLAGS) === added file 'include/grub/bitmap_scale.h' --- include/grub/bitmap_scale.h 1970-01-01 00:00:00 +0000 +++ include/grub/bitmap_scale.h 2009-01-31 20:18:45 +0000 @@ -0,0 +1,48 @@ +/* bitmap_scale.h - Bitmap scaling functions. */ +/* + * GRUB -- GRand Unified Bootloader + * Copyright (C) 2008,2009 Free Software Foundation, Inc. + * + * GRUB 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, either version 3 of the License, or + * (at your option) any later version. + * + * GRUB 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 GRUB. If not, see <http://www.gnu.org/licenses/>. + */ + +#ifndef GRUB_BITMAP_SCALE_HEADER +#define GRUB_BITMAP_SCALE_HEADER 1 + +#include <grub/err.h> +#include <grub/types.h> +#include <grub/bitmap_scale.h> + +enum grub_video_bitmap_scale_method +{ + /* Choose the fastest interpolation algorithm. */ + GRUB_VIDEO_BITMAP_SCALE_METHOD_FASTEST, + /* Choose the highest quality interpolation algorithm. */ + GRUB_VIDEO_BITMAP_SCALE_METHOD_BEST, + + /* Specific algorithms: */ + /* Nearest neighbor interpolation. */ + GRUB_VIDEO_BITMAP_SCALE_METHOD_NEAREST, + /* Bilinear interpolation. */ + GRUB_VIDEO_BITMAP_SCALE_METHOD_BILINEAR +}; + +grub_err_t +grub_video_bitmap_create_scaled (struct grub_video_bitmap **dst, + int dst_width, int dst_height, + struct grub_video_bitmap *src, + enum + grub_video_bitmap_scale_method scale_method); + +#endif /* ! GRUB_BITMAP_SCALE_HEADER */ === modified file 'term/gfxterm.c' --- term/gfxterm.c 2009-01-19 17:09:53 +0000 +++ term/gfxterm.c 2009-01-31 20:28:20 +0000 @@ -27,6 +27,7 @@ #include <grub/env.h> #include <grub/video.h> #include <grub/bitmap.h> +#include <grub/bitmap_scale.h> #define DEFAULT_VIDEO_WIDTH 640 #define DEFAULT_VIDEO_HEIGHT 480 @@ -1095,8 +1096,18 @@ dirty_region_redraw (); } + +/* Option array indices. */ +#define BACKGROUND_CMD_ARGINDEX_MODE 0 + +static const struct grub_arg_option background_image_cmd_options[] = { + {"mode", 'm', 0, "Background image mode (`stretch', `normal').", 0, + ARG_TYPE_STRING}, + {0, 0, 0, 0, 0, 0} +}; + static grub_err_t -grub_gfxterm_background_image_cmd (struct grub_arg_list *state __attribute__ ((unused)), +grub_gfxterm_background_image_cmd (struct grub_arg_list *state, int argc, char **args) { @@ -1123,12 +1134,36 @@ if (grub_errno != GRUB_ERR_NONE) return grub_errno; + /* Determine if the bitmap should be scaled to fit the screen. */ + if (!state[BACKGROUND_CMD_ARGINDEX_MODE].set + || grub_strcmp (state[BACKGROUND_CMD_ARGINDEX_MODE].arg, + "stretch") == 0) + { + if (mode_info.width != grub_video_bitmap_get_width (bitmap) + || mode_info.height != grub_video_bitmap_get_height (bitmap)) + { + struct grub_video_bitmap *scaled_bitmap; + grub_video_bitmap_create_scaled (&scaled_bitmap, + mode_info.width, + mode_info.height, + bitmap, + GRUB_VIDEO_BITMAP_SCALE_METHOD_BEST); + if (grub_errno == GRUB_ERR_NONE) + { + /* Replace the original bitmap with the scaled one. */ + grub_video_bitmap_destroy (bitmap); + bitmap = scaled_bitmap; + } + } + } + + /* If bitmap was loaded correctly, display it. */ if (bitmap) { /* Determine bitmap dimensions. */ bitmap_width = grub_video_bitmap_get_width (bitmap); - bitmap_height = grub_video_bitmap_get_width (bitmap); + bitmap_height = grub_video_bitmap_get_height (bitmap); /* Mark whole screen as dirty. */ dirty_region_reset (); @@ -1171,7 +1206,7 @@ GRUB_COMMAND_FLAG_BOTH, "background_image", "Load background image for active terminal", - 0); + background_image_cmd_options); } GRUB_MOD_FINI(term_gfxterm) === added file 'video/bitmap_scale.c' --- video/bitmap_scale.c 1970-01-01 00:00:00 +0000 +++ video/bitmap_scale.c 2009-01-31 20:22:55 +0000 @@ -0,0 +1,307 @@ +/* bitmap_scale.c - Bitmap scaling. */ +/* + * GRUB -- GRand Unified Bootloader + * Copyright (C) 2006,2007,2008,2009 Free Software Foundation, Inc. + * + * GRUB 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, either version 3 of the License, or + * (at your option) any later version. + * + * GRUB 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 GRUB. If not, see <http://www.gnu.org/licenses/>. + */ + +#include <grub/mm.h> +#include <grub/misc.h> +#include <grub/video.h> +#include <grub/bitmap.h> +#include <grub/bitmap_scale.h> +#include <grub/types.h> + +/* Prototypes for module-local functions. */ +static grub_err_t scale_nn (struct grub_video_bitmap *dst, + struct grub_video_bitmap *src); +static grub_err_t scale_bilinear (struct grub_video_bitmap *dst, + struct grub_video_bitmap *src); + +/* This function creates a new scaled version of the bitmap SRC. The new + bitmap has dimensions DST_WIDTH by DST_HEIGHT. The scaling algorithm + is given by SCALE_METHOD. If an error is encountered, the return code is + not equal to GRUB_ERR_NONE, and the bitmap DST is either not created, or + it is destroyed before this function returns. + + Supports only direct color modes which have components separated + into bytes (e.g., RGBA 8:8:8:8 or BGR 8:8:8 true color). + But because of this simplifying assumption, the implementation is + greatly simplified. */ +grub_err_t +grub_video_bitmap_create_scaled (struct grub_video_bitmap **dst, + int dst_width, int dst_height, + struct grub_video_bitmap *src, + enum grub_video_bitmap_scale_method + scale_method) +{ + *dst = 0; + + /* Verify the simplifying assumptions. */ + if (src == 0) + return grub_error (GRUB_ERR_BAD_ARGUMENT, + "null src bitmap in grub_video_bitmap_create_scaled"); + if (src->mode_info.red_field_pos % 8 != 0 + || src->mode_info.green_field_pos % 8 != 0 + || src->mode_info.blue_field_pos % 8 != 0 + || src->mode_info.reserved_field_pos % 8 != 0) + return grub_error (GRUB_ERR_BAD_ARGUMENT, + "src format not supported for scale"); + if (src->mode_info.width == 0 || src->mode_info.height == 0) + return grub_error (GRUB_ERR_BAD_ARGUMENT, "bitmap has a zero dimension"); + if (dst_width <= 0 || dst_height <= 0) + return grub_error (GRUB_ERR_BAD_ARGUMENT, + "requested to scale to a size w/ a zero dimension"); + if (src->mode_info.bytes_per_pixel * 8 != src->mode_info.bpp) + return grub_error (GRUB_ERR_BAD_ARGUMENT, + "bitmap to scale has inconsistent Bpp and bpp"); + + /* Create the new bitmap. */ + grub_err_t ret; + ret = grub_video_bitmap_create (dst, dst_width, dst_height, + src->mode_info.blit_format); + if (ret != GRUB_ERR_NONE) + return ret; /* Error. */ + + switch (scale_method) + { + case GRUB_VIDEO_BITMAP_SCALE_METHOD_FASTEST: + case GRUB_VIDEO_BITMAP_SCALE_METHOD_NEAREST: + ret = scale_nn (*dst, src); + break; + case GRUB_VIDEO_BITMAP_SCALE_METHOD_BEST: + case GRUB_VIDEO_BITMAP_SCALE_METHOD_BILINEAR: + ret = scale_bilinear (*dst, src); + break; + default: + ret = grub_error (GRUB_ERR_BAD_ARGUMENT, "Invalid scale_method value"); + break; + } + + if (ret == GRUB_ERR_NONE) + { + /* Success: *dst is now a pointer to the scaled bitmap. */ + return GRUB_ERR_NONE; + } + else + { + /* Destroy the bitmap and return the error code. */ + grub_video_bitmap_destroy (*dst); + *dst = 0; + return ret; + } +} + +/* Nearest neighbor bitmap scaling algorithm. + + Copy the bitmap SRC to the bitmap DST, scaling the bitmap to fit the + dimensions of DST. This function uses the nearest neighbor algorithm to + interpolate the pixels. + + Supports only direct color modes which have components separated + into bytes (e.g., RGBA 8:8:8:8 or BGR 8:8:8 true color). + But because of this simplifying assumption, the implementation is + greatly simplified. */ +static grub_err_t +scale_nn (struct grub_video_bitmap *dst, struct grub_video_bitmap *src) +{ + /* Verify the simplifying assumptions. */ + if (dst == 0 || src == 0) + return grub_error (GRUB_ERR_BAD_ARGUMENT, "null bitmap in scale_nn"); + if (dst->mode_info.red_field_pos % 8 != 0 + || dst->mode_info.green_field_pos % 8 != 0 + || dst->mode_info.blue_field_pos % 8 != 0 + || dst->mode_info.reserved_field_pos % 8 != 0) + return grub_error (GRUB_ERR_BAD_ARGUMENT, "dst format not supported"); + if (src->mode_info.red_field_pos % 8 != 0 + || src->mode_info.green_field_pos % 8 != 0 + || src->mode_info.blue_field_pos % 8 != 0 + || src->mode_info.reserved_field_pos % 8 != 0) + return grub_error (GRUB_ERR_BAD_ARGUMENT, "src format not supported"); + if (dst->mode_info.red_field_pos != src->mode_info.red_field_pos + || dst->mode_info.red_mask_size != src->mode_info.red_mask_size + || dst->mode_info.green_field_pos != src->mode_info.green_field_pos + || dst->mode_info.green_mask_size != src->mode_info.green_mask_size + || dst->mode_info.blue_field_pos != src->mode_info.blue_field_pos + || dst->mode_info.blue_mask_size != src->mode_info.blue_mask_size + || dst->mode_info.reserved_field_pos != + src->mode_info.reserved_field_pos + || dst->mode_info.reserved_mask_size != + src->mode_info.reserved_mask_size) + return grub_error (GRUB_ERR_BAD_ARGUMENT, "dst and src not compatible"); + if (dst->mode_info.bytes_per_pixel != src->mode_info.bytes_per_pixel) + return grub_error (GRUB_ERR_BAD_ARGUMENT, "dst and src not compatible"); + if (dst->mode_info.width == 0 || dst->mode_info.height == 0 + || src->mode_info.width == 0 || src->mode_info.height == 0) + return grub_error (GRUB_ERR_BAD_ARGUMENT, "bitmap has a zero dimension"); + + grub_uint8_t *ddata = dst->data; + grub_uint8_t *sdata = src->data; + int dw = dst->mode_info.width; + int dh = dst->mode_info.height; + int sw = src->mode_info.width; + int sh = src->mode_info.height; + int dstride = dst->mode_info.pitch; + int sstride = src->mode_info.pitch; + /* bytes_per_pixel is the same for both src and dst. */ + int bytes_per_pixel = dst->mode_info.bytes_per_pixel; + + int dy; + for (dy = 0; dy < dh; dy++) + { + int dx; + for (dx = 0; dx < dw; dx++) + { + grub_uint8_t *dptr; + grub_uint8_t *sptr; + int sx; + int sy; + int comp; + + /* Compute the source coordinate that the destination coordinate + maps to. Note: sx/sw = dx/dw => sx = sw*dx/dw. */ + sx = sw * dx / dw; + sy = sh * dy / dh; + + /* Get the address of the pixels in src and dst. */ + dptr = ddata + dy * dstride + dx * bytes_per_pixel; + sptr = sdata + sy * sstride + sx * bytes_per_pixel; + + /* Copy the pixel color value. */ + for (comp = 0; comp < bytes_per_pixel; comp++) + dptr[comp] = sptr[comp]; + } + } + return GRUB_ERR_NONE; +} + +/* Bilinear interpolation image scaling algorithm. + + Copy the bitmap SRC to the bitmap DST, scaling the bitmap to fit the + dimensions of DST. This function uses the bilinear interpolation algorithm + to interpolate the pixels. + + Supports only direct color modes which have components separated + into bytes (e.g., RGBA 8:8:8:8 or BGR 8:8:8 true color). + But because of this simplifying assumption, the implementation is + greatly simplified. */ +static grub_err_t +scale_bilinear (struct grub_video_bitmap *dst, struct grub_video_bitmap *src) +{ + /* Verify the simplifying assumptions. */ + if (dst == 0 || src == 0) + return grub_error (GRUB_ERR_BAD_ARGUMENT, "null bitmap in scale func"); + if (dst->mode_info.red_field_pos % 8 != 0 + || dst->mode_info.green_field_pos % 8 != 0 + || dst->mode_info.blue_field_pos % 8 != 0 + || dst->mode_info.reserved_field_pos % 8 != 0) + return grub_error (GRUB_ERR_BAD_ARGUMENT, "dst format not supported"); + if (src->mode_info.red_field_pos % 8 != 0 + || src->mode_info.green_field_pos % 8 != 0 + || src->mode_info.blue_field_pos % 8 != 0 + || src->mode_info.reserved_field_pos % 8 != 0) + return grub_error (GRUB_ERR_BAD_ARGUMENT, "src format not supported"); + if (dst->mode_info.red_field_pos != src->mode_info.red_field_pos + || dst->mode_info.red_mask_size != src->mode_info.red_mask_size + || dst->mode_info.green_field_pos != src->mode_info.green_field_pos + || dst->mode_info.green_mask_size != src->mode_info.green_mask_size + || dst->mode_info.blue_field_pos != src->mode_info.blue_field_pos + || dst->mode_info.blue_mask_size != src->mode_info.blue_mask_size + || dst->mode_info.reserved_field_pos != + src->mode_info.reserved_field_pos + || dst->mode_info.reserved_mask_size != + src->mode_info.reserved_mask_size) + return grub_error (GRUB_ERR_BAD_ARGUMENT, "dst and src not compatible"); + if (dst->mode_info.bytes_per_pixel != src->mode_info.bytes_per_pixel) + return grub_error (GRUB_ERR_BAD_ARGUMENT, "dst and src not compatible"); + if (dst->mode_info.width == 0 || dst->mode_info.height == 0 + || src->mode_info.width == 0 || src->mode_info.height == 0) + return grub_error (GRUB_ERR_BAD_ARGUMENT, "bitmap has a zero dimension"); + + grub_uint8_t *ddata = dst->data; + grub_uint8_t *sdata = src->data; + int dw = dst->mode_info.width; + int dh = dst->mode_info.height; + int sw = src->mode_info.width; + int sh = src->mode_info.height; + int dstride = dst->mode_info.pitch; + int sstride = src->mode_info.pitch; + /* bytes_per_pixel is the same for both src and dst. */ + int bytes_per_pixel = dst->mode_info.bytes_per_pixel; + + int dy; + for (dy = 0; dy < dh; dy++) + { + int dx; + for (dx = 0; dx < dw; dx++) + { + grub_uint8_t *dptr; + grub_uint8_t *sptr; + int sx; + int sy; + int comp; + + /* Compute the source coordinate that the destination coordinate + maps to. Note: sx/sw = dx/dw => sx = sw*dx/dw. */ + sx = sw * dx / dw; + sy = sh * dy / dh; + + /* Get the address of the pixels in src and dst. */ + dptr = ddata + dy * dstride + dx * bytes_per_pixel; + sptr = sdata + sy * sstride + sx * bytes_per_pixel; + + /* If we have enough space to do so, use bilinear interpolation. + Otherwise, fall back to nearest neighbor for this pixel. */ + if (sx < sw - 1 && sy < sh - 1) + { + /* Do bilinear interpolation. */ + + /* Fixed-point .8 numbers representing the fraction of the + distance in the x (u) and y (v) direction within the + box of 4 pixels in the source. */ + int u = (256 * sw * dx / dw) - (sx * 256); + int v = (256 * sh * dy / dh) - (sy * 256); + + for (comp = 0; comp < bytes_per_pixel; comp++) + { + /* Get the component's values for the + four source corner pixels. */ + grub_uint8_t f00 = sptr[comp]; + grub_uint8_t f10 = sptr[comp + bytes_per_pixel]; + grub_uint8_t f01 = sptr[comp + sstride]; + grub_uint8_t f11 = sptr[comp + sstride + bytes_per_pixel]; + + /* Do linear interpolations along the top and bottom + rows of the box. */ + grub_uint8_t f0y = (256 - v) * f00 / 256 + v * f01 / 256; + grub_uint8_t f1y = (256 - v) * f10 / 256 + v * f11 / 256; + + /* Interpolate vertically. */ + grub_uint8_t fxy = (256 - u) * f0y / 256 + u * f1y / 256; + + dptr[comp] = fxy; + } + } + else + { + /* Fall back to nearest neighbor interpolation. */ + /* Copy the pixel color value. */ + for (comp = 0; comp < bytes_per_pixel; comp++) + dptr[comp] = sptr[comp]; + } + } + } + return GRUB_ERR_NONE; +}
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