1 #ifndef _MOVIT_RESAMPLE_EFFECT_H
2 #define _MOVIT_RESAMPLE_EFFECT_H 1
4 // High-quality image resizing, either up or down.
6 // The default scaling offered by the GPU (and as used in ResizeEffect)
7 // is bilinear (optionally mipmapped), which is not the highest-quality
8 // choice, especially for upscaling. ResampleEffect offers the three-lobed
9 // Lanczos kernel, which is among the most popular choices in image
10 // processing. While it does have its weaknesses, in particular a certain
11 // ringing/sharpening effect with artifacts that accumulate over several
12 // consecutive resizings, it is generally regarded as the best tradeoff.
14 // Works in two passes; first horizontal, then vertical (ResampleEffect,
15 // which is what the user is intended to use, instantiates two copies of
16 // SingleResamplePassEffect behind the scenes).
27 class SingleResamplePassEffect;
29 class ResampleEffect : public Effect {
33 virtual std::string effect_type_id() const { return "ResampleEffect"; }
35 // We want this for the same reason as ResizeEffect; we could end up scaling
37 virtual bool needs_texture_bounce() const { return true; }
38 virtual bool needs_srgb_primaries() const { return false; }
40 virtual void inform_input_size(unsigned input_num, unsigned width, unsigned height);
42 virtual std::string output_fragment_shader() {
45 virtual void set_gl_state(GLuint glsl_program_num, const std::string &prefix, unsigned *sampler_num) {
49 virtual void rewrite_graph(EffectChain *graph, Node *self);
50 virtual bool set_float(const std::string &key, float value);
55 SingleResamplePassEffect *hpass, *vpass;
56 int input_width, input_height, output_width, output_height;
59 class SingleResamplePassEffect : public Effect {
61 // If parent is non-NULL, calls to inform_input_size will be forwarded,
62 // so that it can inform both passes about the right input and output
64 SingleResamplePassEffect(ResampleEffect *parent);
65 ~SingleResamplePassEffect();
66 virtual std::string effect_type_id() const { return "SingleResamplePassEffect"; }
68 std::string output_fragment_shader();
70 virtual bool needs_texture_bounce() const { return true; }
71 virtual bool needs_srgb_primaries() const { return false; }
72 virtual AlphaHandling alpha_handling() const { return INPUT_PREMULTIPLIED_ALPHA_KEEP_BLANK; }
74 virtual void inform_input_size(unsigned input_num, unsigned width, unsigned height) {
76 parent->inform_input_size(input_num, width, height);
79 virtual bool changes_output_size() const { return true; }
81 virtual void get_output_size(unsigned *width, unsigned *height, unsigned *virtual_width, unsigned *virtual_height) const {
82 *virtual_width = *width = this->output_width;
83 *virtual_height = *height = this->output_height;
86 void set_gl_state(GLuint glsl_program_num, const std::string &prefix, unsigned *sampler_num);
88 enum Direction { HORIZONTAL = 0, VERTICAL = 1 };
91 void update_texture(GLuint glsl_program_num, const std::string &prefix, unsigned *sampler_num);
93 ResampleEffect *parent;
96 int input_width, input_height, output_width, output_height;
97 int last_input_width, last_input_height, last_output_width, last_output_height;
98 int src_bilinear_samples, num_loops;
102 #endif // !defined(_MOVIT_RESAMPLE_EFFECT_H)