From: Steinar H. Gunderson <sgunderson@bigfoot.com>
Date: Sat, 15 Mar 2014 18:13:38 +0000 (+0100)
Subject: Support pad/crop from bottom, not just from the top.
X-Git-Tag: 1.0~9
X-Git-Url: https://git.sesse.net/?p=movit;a=commitdiff_plain;h=e92a5ffa19eb67b4db5af1db8559630139073668

Support pad/crop from bottom, not just from the top.

This is convenient for the FFTs that are coming.
---

diff --git a/padding_effect.cpp b/padding_effect.cpp
index 15381a3..a70025d 100644
--- a/padding_effect.cpp
+++ b/padding_effect.cpp
@@ -14,13 +14,15 @@ PaddingEffect::PaddingEffect()
 	  output_width(1280),
 	  output_height(720),
 	  top(0),
-	  left(0)
+	  left(0),
+	  pad_from_bottom(0)
 {
 	register_vec4("border_color", (float *)&border_color);
 	register_int("width", &output_width);
 	register_int("height", &output_height);
 	register_float("top", &top);
 	register_float("left", &left);
+	register_int("pad_from_bottom", &pad_from_bottom);
 }
 
 string PaddingEffect::output_fragment_shader()
@@ -32,10 +34,13 @@ void PaddingEffect::set_gl_state(GLuint glsl_program_num, const string &prefix,
 {
 	Effect::set_gl_state(glsl_program_num, prefix, sampler_num);
 
-	float offset[2] = {
-		left / output_width,
-		(output_height - input_height - top) / output_height
-	};
+	float offset[2];
+	offset[0] = left / output_width;
+	if (pad_from_bottom) {
+		offset[1] = top / output_height;
+	} else {
+		offset[1] = (output_height - input_height - top) / output_height;
+	}
 	set_uniform_vec2(glsl_program_num, prefix, "offset", offset);
 
 	float scale[2] = {
diff --git a/padding_effect.h b/padding_effect.h
index 3bd4aac..fdefbe0 100644
--- a/padding_effect.h
+++ b/padding_effect.h
@@ -11,6 +11,10 @@
 // The border color is taken to be in linear gamma, sRGB, with premultiplied alpha.
 // You may not change it after calling finalize(), since that could change the
 // graph (need_linear_light() etc. depend on the border color you choose).
+//
+// As a convenience, if the flag “pad_from_bottom” is nonzero, the “top” parameter
+// will mean pixels from the bottom (matching OpenGL's usual bottom-left convention),
+// instead of from the top as usual.
 
 #include <GL/glew.h>
 #include <string>
@@ -39,6 +43,7 @@ private:
 	int input_width, input_height;
 	int output_width, output_height;
 	float top, left;
+	int pad_from_bottom;
 };
 
 }  // namespace movit
diff --git a/padding_effect_test.cpp b/padding_effect_test.cpp
index 767f3e8..8c05a1e 100644
--- a/padding_effect_test.cpp
+++ b/padding_effect_test.cpp
@@ -208,6 +208,37 @@ TEST(PaddingEffectTest, Crop) {
 	expect_equal(expected_data, out_data, 1, 1);
 }
 
+TEST(PaddingEffectTest, CropFromBottom) {
+	float data[2 * 2] = {
+		1.0f, 0.5f,
+		0.8f, 0.3f,
+	};
+	float expected_data[1 * 1] = {
+		0.5f,
+	};
+	float out_data[1 * 1];
+
+	EffectChainTester tester(NULL, 1, 1);
+
+	ImageFormat format;
+	format.color_space = COLORSPACE_sRGB;
+	format.gamma_curve = GAMMA_LINEAR;
+
+	FlatInput *input = new FlatInput(format, FORMAT_GRAYSCALE, GL_FLOAT, 2, 2);
+	input->set_pixel_data(data);
+	tester.get_chain()->add_input(input);
+
+	Effect *effect = tester.get_chain()->add_effect(new PaddingEffect());
+	CHECK(effect->set_int("width", 1));
+	CHECK(effect->set_int("height", 1));
+	CHECK(effect->set_float("left", -1.0f));
+	CHECK(effect->set_float("top", -1.0f));
+	CHECK(effect->set_int("pad_from_bottom", 1));
+
+	tester.run(out_data, GL_RED, COLORSPACE_sRGB, GAMMA_LINEAR, OUTPUT_ALPHA_FORMAT_PREMULTIPLIED);
+	expect_equal(expected_data, out_data, 1, 1);
+}
+
 TEST(PaddingEffectTest, AlphaIsCorrectEvenWithNonLinearInputsAndOutputs) {
 	float data[2 * 1] = {
 		1.0f,