From eff515337553846bf57881670305d35ad92966dc Mon Sep 17 00:00:00 2001
From: Relintai <relintai@protonmail.com>
Date: Mon, 8 Aug 2022 02:39:21 +0200
Subject: [PATCH] Backported convert_rg_to_ra_rgba8 and convert_ra_rgba8_to_rg
 from Godot4's Image.

---
 core/image.cpp | 31 +++++++++++++++++++++++++++++++
 core/image.h   |  3 +++
 2 files changed, 34 insertions(+)

diff --git a/core/image.cpp b/core/image.cpp
index a1e7485e1..741e61806 100644
--- a/core/image.cpp
+++ b/core/image.cpp
@@ -2972,6 +2972,9 @@ void Image::_bind_methods() {
 	ClassDB::bind_method(D_METHOD("load_tga_from_buffer", "buffer"), &Image::load_tga_from_buffer);
 	ClassDB::bind_method(D_METHOD("load_bmp_from_buffer", "buffer"), &Image::load_bmp_from_buffer);
 
+	ClassDB::bind_method(D_METHOD("convert_rg_to_ra_rgba8"), &Image::convert_rg_to_ra_rgba8);
+	ClassDB::bind_method(D_METHOD("convert_ra_rgba8_to_rg"), &Image::convert_ra_rgba8_to_rg);
+
 	ADD_PROPERTY(PropertyInfo(Variant::DICTIONARY, "data", PROPERTY_HINT_NONE, "", PROPERTY_USAGE_STORAGE), "_set_data", "_get_data");
 
 	BIND_CONSTANT(MAX_WIDTH);
@@ -3300,6 +3303,34 @@ Error Image::load_bmp_from_buffer(const PoolVector<uint8_t> &p_array) {
 	return _load_from_buffer(p_array, _bmp_mem_loader_func);
 }
 
+void Image::convert_rg_to_ra_rgba8() {
+	ERR_FAIL_COND(format != FORMAT_RGBA8);
+	ERR_FAIL_COND(!data.size());
+
+	int s = data.size();
+	PoolVector<uint8_t>::Write pw = data.write();
+	uint8_t *w = pw.ptr();
+	for (int i = 0; i < s; i += 4) {
+		w[i + 3] = w[i + 1];
+		w[i + 1] = 0;
+		w[i + 2] = 0;
+	}
+}
+
+void Image::convert_ra_rgba8_to_rg() {
+	ERR_FAIL_COND(format != FORMAT_RGBA8);
+	ERR_FAIL_COND(!data.size());
+
+	int s = data.size();
+	PoolVector<uint8_t>::Write pw = data.write();
+	uint8_t *w = pw.ptr();
+	for (int i = 0; i < s; i += 4) {
+		w[i + 1] = w[i + 3];
+		w[i + 2] = 0;
+		w[i + 3] = 255;
+	}
+}
+
 Error Image::_load_from_buffer(const PoolVector<uint8_t> &p_array, ImageMemLoadFunc p_loader) {
 	int buffer_size = p_array.size();
 
diff --git a/core/image.h b/core/image.h
index e8889d17a..86b40978f 100644
--- a/core/image.h
+++ b/core/image.h
@@ -343,6 +343,9 @@ public:
 	Error load_tga_from_buffer(const PoolVector<uint8_t> &p_array);
 	Error load_bmp_from_buffer(const PoolVector<uint8_t> &p_array);
 
+	void convert_rg_to_ra_rgba8();
+	void convert_ra_rgba8_to_rg();
+
 	Image(const uint8_t *p_mem_png_jpg, int p_len = -1);
 	Image(const char **p_xpm);