MeowOS
f44e3bc6d0
git-subtree-dir: sdk git-subtree-mainline:17a972d46fgit-subtree-split:2e7561d74f
131 lines
4.5 KiB
C
131 lines
4.5 KiB
C
/*
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* meow_ui_img.c — 图片层（B1.2）。基于 stb_image（单头文件、静态编入），
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* 解 PNG/JPEG/BMP → RGBA，统一最近邻缩放/居中裁方。
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*/
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#include "meow_ui.h"
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#include "meow_ui_internal.h"
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#include "stb_image.h"
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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struct meow_img {
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int w, h;
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unsigned char *rgba; /* 4 通道 straight alpha */
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};
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static meow_img *img_alloc(int w, int h, unsigned char *rgba)
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{
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if (w <= 0 || h <= 0 || !rgba) { if (rgba) stbi_image_free(rgba); return NULL; }
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meow_img *im = (meow_img *)malloc(sizeof *im);
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if (!im) { stbi_image_free(rgba); return NULL; }
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im->w = w; im->h = h; im->rgba = rgba;
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return im;
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}
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meow_img *meow_img_load_mem(const void *buf, int len)
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{
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if (!buf || len <= 0) return NULL;
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int w = 0, h = 0, c = 0;
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unsigned char *p = stbi_load_from_memory((const unsigned char *)buf, len, &w, &h, &c, 4);
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if (!p) return NULL;
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return img_alloc(w, h, p);
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}
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meow_img *meow_img_load_file(const char *path)
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{
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if (!path) return NULL;
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int w = 0, h = 0, c = 0;
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unsigned char *p = stbi_load(path, &w, &h, &c, 4);
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if (!p) return NULL;
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return img_alloc(w, h, p);
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}
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void meow_img_free(meow_img *im)
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{
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if (!im) return;
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if (im->rgba) stbi_image_free(im->rgba);
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free(im);
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}
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int meow_img_w(meow_img *im) { return im ? im->w : 0; }
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int meow_img_h(meow_img *im) { return im ? im->h : 0; }
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/* 最近邻采样缩放（cover=1 居中裁方），返回 dw*dh*4 临时 RGBA 缓冲 */
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static unsigned char *scale_buf(const meow_img *im, int dw, int dh, int cover)
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{
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if (!im || dw <= 0 || dh <= 0) return NULL;
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unsigned char *out = (unsigned char *)malloc((size_t)dw * dh * 4);
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if (!out) return NULL;
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float s = 1.0f;
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if (cover) {
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/* 真正铺满（cover）：每目标像素对应 s 个源像素，s = min(W/dw, H/dh)——缩放后图像
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* 宽/高两维都不小于目标（可能外溢），居中裁方。居中裁剪偏移（源像素）= (W-dw*s)/2
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* 恒 ≥ 0。曾误作 `s = max(sx,sy)` 且采样 `(dx+ox)/s`（除以缩放比）：把整块输出映射到
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* 源左上角 ~dw/s 像素的透明角——图标（透明角 logo）整块透明、不绘制，即
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* 「icon: ... OK 但渲染不出（只显首字母占位）」根因。正确：源索引 = dx*s + 裁剪偏移
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* （与下方非 cover 分支 `dx*im->w/dw` 同一乘向）。 */
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float sx = (float)im->w / dw, sy = (float)im->h / dh;
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s = sx < sy ? sx : sy; /* 源像素/目标像素（铺满 → 取小） */
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float oxs = ((float)im->w - (float)dw * s) * 0.5f; /* 居中裁剪起点（源像素，≥0） */
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float oys = ((float)im->h - (float)dh * s) * 0.5f;
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if (oxs < 0) oxs = 0; if (oys < 0) oys = 0;
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for (int dy = 0; dy < dh; dy++) {
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int syi = (int)((float)dy * s + oys);
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if (syi < 0) syi = 0; if (syi >= im->h) syi = im->h - 1;
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for (int dx = 0; dx < dw; dx++) {
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int sxi = (int)((float)dx * s + oxs);
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if (sxi < 0) sxi = 0; if (sxi >= im->w) sxi = im->w - 1;
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memcpy(out + ((size_t)dy * dw + dx) * 4,
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im->rgba + ((size_t)syi * im->w + sxi) * 4, 4);
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}
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}
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} else {
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for (int dy = 0; dy < dh; dy++) {
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int syi = (int)((float)dy * im->h / dh);
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if (syi >= im->h) syi = im->h - 1;
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for (int dx = 0; dx < dw; dx++) {
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int sxi = (int)((float)dx * im->w / dw);
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if (sxi >= im->w) sxi = im->w - 1;
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memcpy(out + ((size_t)dy * dw + dx) * 4,
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im->rgba + ((size_t)syi * im->w + sxi) * 4, 4);
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}
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}
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}
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return out;
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}
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void meow_ui_img(int x, int y, meow_img *im)
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{
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if (!im) return;
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meow_gfx_blit_rgba(x, y, im->w, im->h, im->rgba, 255);
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}
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void meow_ui_img_scaled(int x, int y, int w, int h, meow_img *im)
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{
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if (!im) return;
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unsigned char *tmp = scale_buf(im, w, h, 0);
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if (!tmp) return;
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meow_gfx_blit_rgba(x, y, w, h, tmp, 255);
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free(tmp);
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}
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void meow_ui_img_alpha(int x, int y, int w, int h, meow_img *im, int alpha)
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{
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if (!im) return;
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unsigned char *tmp = scale_buf(im, w, h, 0);
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if (!tmp) return;
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meow_gfx_blit_rgba(x, y, w, h, tmp, alpha);
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free(tmp);
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}
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void meow_ui_img_cover(int x, int y, int size, meow_img *im)
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{
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if (!im) return;
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unsigned char *tmp = scale_buf(im, size, size, 1);
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if (!tmp) return;
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meow_gfx_blit_rgba(x, y, size, size, tmp, 255);
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free(tmp);
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}
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