4 #include "effect_util.h"
5 #include "padding_effect.h"
12 PaddingEffect::PaddingEffect()
13 : border_color(0.0f, 0.0f, 0.0f, 0.0f),
20 register_vec4("border_color", (float *)&border_color);
21 register_int("width", &output_width);
22 register_int("height", &output_height);
23 register_float("top", &top);
24 register_float("left", &left);
25 register_int("pad_from_bottom", &pad_from_bottom);
28 string PaddingEffect::output_fragment_shader()
30 return read_file("padding_effect.frag");
33 void PaddingEffect::set_gl_state(GLuint glsl_program_num, const string &prefix, unsigned *sampler_num)
35 Effect::set_gl_state(glsl_program_num, prefix, sampler_num);
38 offset[0] = left / output_width;
39 if (pad_from_bottom) {
40 offset[1] = top / output_height;
42 offset[1] = (output_height - input_height - top) / output_height;
44 set_uniform_vec2(glsl_program_num, prefix, "offset", offset);
47 float(output_width) / input_width,
48 float(output_height) / input_height
50 set_uniform_vec2(glsl_program_num, prefix, "scale", scale);
52 // Due to roundoff errors, the test against 0.5 is seldom exact,
53 // even though we test for less than and not less-than-or-equal.
54 // We'd rather keep an extra border pixel in those very rare cases
55 // (where the image is shifted pretty much exactly a half-pixel)
56 // than losing a pixel in the common cases of integer shift.
57 // Thus the 1e-3 fudge factors.
58 float texcoord_min[2] = {
59 float((0.5f - 1e-3) / input_width),
60 float((0.5f - 1e-3) / input_height)
62 set_uniform_vec2(glsl_program_num, prefix, "texcoord_min", texcoord_min);
64 float texcoord_max[2] = {
65 float(1.0f - (0.5f - 1e-3) / input_width),
66 float(1.0f - (0.5f - 1e-3) / input_height)
68 set_uniform_vec2(glsl_program_num, prefix, "texcoord_max", texcoord_max);
71 // We don't change the pixels of the image itself, so the only thing that
72 // can make us less flexible is if the border color can be interpreted
73 // differently in different modes.
75 // 0.0 and 1.0 are interpreted the same, no matter the gamma ramp.
76 // Alpha is not affected by gamma per se, but the combination of
77 // premultiplied alpha and non-linear gamma curve does not make sense,
78 // so if could possibly be converting blank alpha to non-blank
79 // (ie., premultiplied), we need our output to be in linear light.
80 bool PaddingEffect::needs_linear_light() const
82 if ((border_color.r == 0.0 || border_color.r == 1.0) &&
83 (border_color.g == 0.0 || border_color.g == 1.0) &&
84 (border_color.b == 0.0 || border_color.b == 1.0) &&
85 border_color.a == 1.0) {
91 // The white point is the same (D65) in all the color spaces we currently support,
92 // so any gray would be okay, but we don't really have a guarantee for that.
93 // Stay safe and say that only pure black and pure white is okay.
94 // Alpha is not affected by color space.
95 bool PaddingEffect::needs_srgb_primaries() const
97 if (border_color.r == 0.0 && border_color.g == 0.0 && border_color.b == 0.0) {
100 if (border_color.r == 1.0 && border_color.g == 1.0 && border_color.b == 1.0) {
106 Effect::AlphaHandling PaddingEffect::alpha_handling() const
108 // If the border color is black, it doesn't matter if we're pre- or postmultiplied.
109 // Note that for non-solid black (i.e. alpha < 1.0), we're equally fine with
110 // pre- and postmultiplied, but later effects might change this status
111 // (consider e.g. blur), so setting DONT_CARE_ALPHA_TYPE is inappropriate,
112 // as it propagate blank alpha through this effect.
113 if (border_color.r == 0.0 && border_color.g == 0.0 && border_color.b == 0.0 && border_color.a == 1.0) {
114 return DONT_CARE_ALPHA_TYPE;
117 // If the border color is solid, we preserve blank alpha, as we never output any
118 // new non-solid pixels.
119 if (border_color.a == 1.0) {
120 return INPUT_PREMULTIPLIED_ALPHA_KEEP_BLANK;
123 // Otherwise, we're going to output our border color in premultiplied alpha,
124 // so the other pixels better be premultiplied as well.
125 return INPUT_AND_OUTPUT_PREMULTIPLIED_ALPHA;
128 void PaddingEffect::get_output_size(unsigned *width, unsigned *height, unsigned *virtual_width, unsigned *virtual_height) const
130 *virtual_width = *width = output_width;
131 *virtual_height = *height = output_height;
134 void PaddingEffect::inform_input_size(unsigned input_num, unsigned width, unsigned height)
136 assert(input_num == 0);
138 input_height = height;