stbi: add a resize_uint8 function for resizing images in memory (#18484)

thirdparty/stb_image/stbi.c

@@ -1,5 +1,6 @@
 #define STB_IMAGE_IMPLEMENTATION
 #define STB_IMAGE_WRITE_IMPLEMENTATION
+#define STB_IMAGE_RESIZE_IMPLEMENTATION
 
 #include <stddef.h>
 
@@ -16,6 +17,7 @@ extern void   stbi__callback_free(void *ptr);
 
 #include "stb_image.h"
 #include "stb_image_write.h"
+#include "stb_image_resize.h"
 
 /*
 void set_png_compression_level(int level);

vlib/stbi/stbi.c.v

@@ -32,6 +32,7 @@ fn cb_free(p voidptr) {
 #flag -I @VEXEROOT/thirdparty/stb_image
 #include "stb_image.h"
 #include "stb_image_write.h"
+#include "stb_image_resize.h"
 #include "stb_v_header.h"
 #flag @VEXEROOT/thirdparty/stb_image/stbi.o
 
@@ -141,6 +142,36 @@ pub fn load_from_memory(buf &u8, bufsize int) !Image {
 	return res
 }
 
+//-----------------------------------------------------------------------------
+//
+// Resize functions
+//
+//-----------------------------------------------------------------------------
+fn C.stbir_resize_uint8(input_pixels &u8, input_w int, input_h int, input_stride_in_bytes int, output_pixels &u8, output_w int, output_h int, output_stride_in_bytes int, num_channels int) int
+
+// resize_uint8 resizes `img` to dimensions of `output_w` and `output_h`
+pub fn resize_uint8(img &Image, output_w int, output_h int) !Image {
+	mut res := Image{
+		ok: true
+		ext: img.ext
+		data: 0
+		width: output_w
+		height: output_h
+		nr_channels: img.nr_channels
+	}
+
+	res.data = cb_malloc(usize(output_w * output_h * img.nr_channels))
+	if res.data == 0 {
+		return error('stbi_image failed to resize file')
+	}
+
+	if 0 == C.stbir_resize_uint8(img.data, img.width, img.height, 0, res.data, output_w,
+		output_h, 0, img.nr_channels) {
+		return error('stbi_image failed to resize file')
+	}
+	return res
+}
+
 //-----------------------------------------------------------------------------
 //
 // Write functions

vlib/stbi/stbi_test.v

@@ -42,3 +42,30 @@ fn test_stbi_read_write() {
 	assert 0 == delta
 	os.rm(out_path) or {}
 }
+
+fn test_stbi_resize() {
+	vroot := @VEXEROOT
+	path := os.join_path(vroot, 'examples', 'assets', 'logo.png')
+	println('Source path: ${path}')
+	d_s := stbi.load(path) or { panic(err) }
+	println('Image source data:\n ${d_s}')
+
+	new_width, new_height := 100, 100
+
+	d_r := stbi.resize_uint8(d_s, new_width, new_height) or { panic(err) }
+	println('Resized Image source data:\n ${d_s}')
+
+	out_path := os.join_path(tfolder, 'test.png')
+	println('Out path: ${out_path}')
+	stbi.stbi_write_png(out_path, d_r.width, d_r.height, 4, d_r.data, d_r.width * 4) or {
+		panic(err)
+	}
+
+	d_d := stbi.load(out_path) or { panic(err) }
+	println('Image dest data:\n ${d_d}')
+
+	assert d_d.width == new_width
+	assert d_d.height == new_height
+	assert d_d.nr_channels == d_r.nr_channels
+	os.rm(out_path) or {}
+}