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Fixed flicker issues. FindGlyph can now provide a backup glyph if the…
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… requested glyph has not yet been rendered.
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@georgegerdin
georgegerdin committed Sep 27, 2020
1 parent fe1fbb9 commit 986738c
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Showing 3 changed files with 85 additions and 17 deletions.
3 changes: 2 additions & 1 deletion imgui.h
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Expand Up @@ -2250,6 +2250,7 @@ struct ImFontGlyph
int NextGlyph;
short GlyphSize;
ImFontTexture* FontTexture;
int FrameCountCreation; //Frame count when this glyph was rendered
};

struct ImFontQuad
Expand Down Expand Up @@ -2424,7 +2425,7 @@ struct ImFont
// Methods
IMGUI_API ImFont();
IMGUI_API ~ImFont();
IMGUI_API const ImFontGlyph*FindGlyph(ImWchar c, float size);
IMGUI_API const ImFontGlyph*FindGlyph(ImWchar c, float size, ImFontGlyph** backup_glyph = NULL);
// FIXME-DYNAMICFONT: Add support for findglyphnofallback
IMGUI_API const ImFontGlyph*FindGlyphNoFallback(ImWchar c, float size) const;
float GetCharAdvance(ImWchar c, float size);
Expand Down
97 changes: 82 additions & 15 deletions imgui_draw.cpp
View file
Expand Up @@ -1739,6 +1739,17 @@ ImFontAtlas::ImFontAtlas(int tex_width, int tex_height)
//Create data for an empty font texture. This will be used every time a new texture is spawned.
EmptyFontTexturePixelData.resize(TexWidth*TexHeight * 4, 0);

//This turns the font texture green for debugging purposes
/*for(auto x = 0; x < TexWidth; ++x) {
for(auto y = 0; y < TexHeight; ++y) {
auto* pixel = &EmptyFontTexturePixelData[((y*TexWidth) + x) * 4];
pixel[0] = 0;
pixel[1] = 255;
pixel[2] = 0;
pixel[3] = 255;
}
}*/

//Create first font texture
FontTextures.push_back(IM_NEW(ImFontTexture(TexWidth, TexHeight, EmptyFontTexturePixelData.Data)));

Expand Down Expand Up @@ -2466,7 +2477,7 @@ void ImFontAtlas::FindTextureAndRow(ImFontTexture** resulting_texture, ImFontTex
*resulting_texture = (*texture);
}

const ImFontGlyph* ImFont::FindGlyph(ImWchar codepoint, float size)
const ImFontGlyph* ImFont::FindGlyph(ImWchar codepoint, float size, ImFontGlyph** backup_glyph)
{

int i, g, advance, lsb, x0, y0, x1, y1;
Expand All @@ -2475,13 +2486,34 @@ const ImFontGlyph* ImFont::FindGlyph(ImWchar codepoint, float size)
// Find code point and size using lookup table.
unsigned int h = hashint(codepoint) & (IM_HASH_LUT_SIZE - 1);
i = this->lut[h];
ImFontGlyph* result = NULL;
if(backup_glyph) *backup_glyph = NULL;
while (i != -1)
{
if (this->Glyphs[i].Codepoint == codepoint && this->Glyphs[i].GlyphSize == (short) size)
return &this->Glyphs[i];
if (this->Glyphs[i].Codepoint == codepoint) {
if(this->Glyphs[i].GlyphSize == (short) size && !result) {
result = &this->Glyphs[i]; // Save the result
if(!backup_glyph) break; //Caller didn't want a backup glyph
if((this->Glyphs[i].FontTexture && this->Glyphs[i].FontTexture->TexID != NULL) && this->Glyphs[i].FrameCountCreation != ImGui::GetFrameCount()) {
*backup_glyph = NULL; // This glyph has already been rendered and uploeaded to the graphics card. No backup glyph needed.
break;
}
if(*backup_glyph)
break; //We have already found a backup glyph
//We have found the glyph but we still need a backup glyph
}
else if(backup_glyph && *backup_glyph == NULL) {
if(this->Glyphs[i].FontTexture && this->Glyphs[i].FontTexture->TexID && this->Glyphs[i].FrameCountCreation != ImGui::GetFrameCount()) { //Make sure the backup glyph has been rendered and uploaded
*backup_glyph = &this->Glyphs[i]; // Save this as a backup
if(result) break; //Both primary glyph and backup has been found
}
}
}
i = this->Glyphs[i].NextGlyph;
}

if(result) return result;

// Create this glyph.
float scale = FONT_ScaleForPixelHeight(this->PrivData, size);

Expand Down Expand Up @@ -2516,6 +2548,7 @@ const ImFontGlyph* ImFont::FindGlyph(ImWchar codepoint, float size)
glyph.Xoff = (float)x0;
glyph.Yoff = (float)y0;
glyph.NextGlyph = this->lut[h];
glyph.FrameCountCreation = ImGui::GetFrameCount();

// Advance row location.
br->x += gw + 1;
Expand Down Expand Up @@ -2791,31 +2824,45 @@ void ImFont::RenderChar(ImDrawList* draw_list, float size, ImVec2 pos, ImU32 col
{
if (c == ' ' || c == '\t' || c == '\n' || c == '\r') // Match behavior of RenderText(), those 4 codepoints are hard-coded.
return;
if (const ImFontGlyph* glyph = FindGlyph((unsigned int)c, size))
ImFontGlyph* backup_glyph = NULL;
if (const ImFontGlyph* glyph = FindGlyph((unsigned int)c, size, &backup_glyph))
{
float ascender = IM_FLOOR(Ascent * size);
pos.x = IM_FLOOR(pos.x + DisplayOffset.x);
pos.y = IM_FLOOR(pos.y + DisplayOffset.y);
int texture_width = glyph->FontTexture->TexWidth;
int texture_height = glyph->FontTexture->TexHeight;

ImFontTexture* glyph_texture = glyph->FontTexture;

ImFontQuad q = GetQuad(*glyph, pos.x, pos.y);

float x1 = q.x0;
float x2 = q.x1;
float y1 = ascender + q.y0;
float y2 = ascender + q.y1;

//If this glyph has not yet been rendered and uploaded to the video card
//render a stretched backup glyph instead
if(backup_glyph && (glyph_texture->TexID == NULL || glyph->FrameCountCreation == ImGui::GetFrameCount())) { // It takes a frame for the glyph to be uploaded
glyph_texture = backup_glyph->FontTexture;
q = GetQuad(*backup_glyph, pos.x, pos.y);
}

float u1 = q.u0;
float v1 = q.v0;
float u2 = q.u1;
float v2 = q.v1;

int texture_width = glyph_texture->TexWidth;
int texture_height = glyph_texture->TexHeight;

u1 /= texture_width;
u2 /= texture_width;
v1 /= texture_height;
v2 /= texture_height;

// FIXME-DYNAMICFONT: Shouldn't use AddImageQuad
draw_list->AddImageQuad(
glyph->FontTexture->TexID,
glyph_texture->TexID,
ImVec2(x1, y1),
ImVec2(x2, y1),
ImVec2(x2, y2),
Expand Down Expand Up @@ -2959,18 +3006,29 @@ void ImFont::RenderText(ImDrawList* draw_list, float size, ImVec2 pos, ImU32 col

float char_width = 0.0f;
float ascender = ImFloor(Ascent * size);
if (const ImFontGlyph* glyph = FindGlyph((ImWchar)c, size))
ImFontGlyph* backup_glyph = NULL; //If the correct glyph has not yet been rendered
if (const ImFontGlyph* glyph = FindGlyph((ImWchar)c, size, &backup_glyph))
{
int texture_width = glyph->FontTexture->TexWidth;
int texture_height = glyph->FontTexture->TexHeight;
ImFontTexture* glyph_texture = glyph->FontTexture;

//If this glyph has not yet been rendered and uploaded to the video card
//render a stretched backup glyph instead
bool using_backup_glyph = false;
if(backup_glyph && (glyph_texture->TexID == NULL || glyph->FrameCountCreation == ImGui::GetFrameCount())) { // It takes a frame for the glyph to be uploaded
glyph_texture = backup_glyph->FontTexture;
using_backup_glyph = true;
}

int texture_width = glyph_texture->TexWidth;
int texture_height = glyph_texture->TexHeight;

char_width = IM_ROUND(glyph->AdvanceX);/* scale*/

// Arbitrarily assume that both space and tabs are empty glyphs as an optimization
if (c != ' ' && c != '\t' && glyph->FontTexture->TexID)
if (c != ' ' && c != '\t' && glyph_texture->TexID)
{
if (!texture_selected) { //When rendering the first char we select our default texture
selected_texture = glyph->FontTexture->TexID;
selected_texture = glyph_texture->TexID;
if (draw_list->_CmdHeader.TextureId != selected_texture) {
draw_list->PushTextureID(selected_texture);
pushed_texture = true; // We need to pop later
Expand All @@ -2986,13 +3044,13 @@ void ImFont::RenderText(ImDrawList* draw_list, float size, ImVec2 pos, ImU32 col
texture_selected = true;
}

if (glyph->FontTexture->TexID != selected_texture) {//Save the glyph for later rendering
if (glyph_texture->TexID != selected_texture) {//Save the glyph for later rendering
FontRenderList* render_list = NULL;

// Find the render list for this texture
for (FontRenderList** rlist = font_render_list.begin(); rlist != font_render_list.end(); rlist++) {
FontRenderList* rlist_ref = *rlist;
if (rlist_ref->TexID == glyph->FontTexture->TexID) {
if (rlist_ref->TexID == glyph_texture->TexID) {
render_list = rlist_ref;
break;
}
Expand All @@ -3001,7 +3059,7 @@ void ImFont::RenderText(ImDrawList* draw_list, float size, ImVec2 pos, ImU32 col
if (!render_list) { // Render list for this texture not found
//Create render list for this texture
render_list = IM_NEW(FontRenderList);
render_list->TexID = glyph->FontTexture->TexID;
render_list->TexID = glyph_texture->TexID;
render_list->VtxBuffer.resize(vtx_count_max);
render_list->IdxBuffer.resize(idx_count_max);
render_list->vtx_write = render_list->VtxBuffer.Data;
Expand All @@ -3019,6 +3077,10 @@ void ImFont::RenderText(ImDrawList* draw_list, float size, ImVec2 pos, ImU32 col
float y2 = ascender + q.y1 /* scale*/;
if (x1 <= clip_rect.z && x2 >= clip_rect.x)
{
//If using a backup glyph we need to change the texture UV's
if(using_backup_glyph) {
q = GetQuad(*backup_glyph, x, y);
}
// Render a character
float u1 = q.u0;
float v1 = q.v0;
Expand Down Expand Up @@ -3107,6 +3169,11 @@ void ImFont::RenderText(ImDrawList* draw_list, float size, ImVec2 pos, ImU32 col
float y2 = ascender + q.y1 /* scale*/;
if (x1 <= clip_rect.z && x2 >= clip_rect.x)
{
//If using a backup glyph we need to change the texture UV's
if(using_backup_glyph) {
q = GetQuad(*backup_glyph, x, y);
}

// Render a character
float u1 = q.u0;
float v1 = q.v0;
Expand Down
2 changes: 1 addition & 1 deletion imgui_widgets.cpp
View file
Expand Up @@ -3944,7 +3944,7 @@ bool ImGui::InputTextEx(const char* label, const char* hint, char* buf, int buf_
// Password pushes a temporary font with only a fallback glyph
if (is_password && !is_displaying_hint)
{
const ImFontGlyph* glyph = g.Font->FindGlyph('*', g.FontSize);
const ImFontGlyph* glyph = g.Font->FindGlyph('*', g.FontSize);
ImFont* password_font = &g.InputTextPasswordFont;
//password_font->FontSize = g.Font->FontSize;
password_font->Scale = g.Font->Scale;
Expand Down

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