InputText: Fixed password fields displaying ASCII spaces as blanks. Fixed non-ASCII space occasionally creating unnecessary empty polygons. (#2149, #515)

docs/CHANGELOG.txt

@@ -38,6 +38,9 @@ Other Changes:
 
 - ColorButton: Added ImGuiColorEditFlags_NoBorder flag to remove the border normally enforced
   by default for standalone ColorButton.
+- InputText: Fixed password fields displaying ASCII spaces as blanks instead of using the '*'
+  glyph. (#2149, #515)
+- Font: Fixed non-ASCII space occasionally creating unnecessary empty polygons.
 - Demo: Added a black and white gradient to Demo>Examples>Custom Rendering.
 - Backends: SDL: Added ImGui_ImplSDL2_InitForMetal() for API consistency (even though the function
   currently does nothing).

imgui.h

@@ -2068,9 +2068,12 @@ struct ImFontConfig
     IMGUI_API ImFontConfig();
 };
 
+// Hold rendering data for one glyph.
+// (Note: some language parsers may fail to convert the 31+1 bitfield members, in this case maybe drop store a single u32 or we can rework this)
 struct ImFontGlyph
 {
-    ImWchar         Codepoint;          // 0x0000..0xFFFF
+    unsigned int    Codepoint : 31;     // 0x0000..0xFFFF
+    unsigned int    Visible : 1;        // Flag to allow early out when rendering
     float           AdvanceX;           // Distance to next character (= data from font + ImFontConfig::GlyphExtraSpacing.x baked in)
     float           X0, Y0, X1, Y1;     // Glyph corners
     float           U0, V0, U1, V1;     // Texture coordinates
@@ -2265,6 +2268,7 @@ struct ImFont
     IMGUI_API void              GrowIndex(int new_size);
     IMGUI_API void              AddGlyph(ImWchar c, float x0, float y0, float x1, float y1, float u0, float v0, float u1, float v1, float advance_x);
     IMGUI_API void              AddRemapChar(ImWchar dst, ImWchar src, bool overwrite_dst = true); // Makes 'dst' character/glyph points to 'src' character/glyph. Currently needs to be called AFTER fonts have been built.
+    IMGUI_API void              SetGlyphVisible(ImWchar c, bool visible);
     IMGUI_API void              SetFallbackChar(ImWchar c);
 };
 

imgui_demo.cpp

@@ -1040,11 +1040,11 @@ static void ShowDemoWindowWidgets()
             static char buf6[64] = ""; ImGui::InputText("\"imgui\" letters", buf6, 64, ImGuiInputTextFlags_CallbackCharFilter, TextFilters::FilterImGuiLetters);
 
             ImGui::Text("Password input");
-            static char bufpass[64] = "password123";
-            ImGui::InputText("password", bufpass, 64, ImGuiInputTextFlags_Password | ImGuiInputTextFlags_CharsNoBlank);
+            static char password[64] = "password123";
+            ImGui::InputText("password", password, IM_ARRAYSIZE(password), ImGuiInputTextFlags_Password);
             ImGui::SameLine(); HelpMarker("Display all characters as '*'.\nDisable clipboard cut and copy.\nDisable logging.\n");
-            ImGui::InputTextWithHint("password (w/ hint)", "<password>", bufpass, 64, ImGuiInputTextFlags_Password | ImGuiInputTextFlags_CharsNoBlank);
-            ImGui::InputText("password (clear)", bufpass, 64, ImGuiInputTextFlags_CharsNoBlank);
+            ImGui::InputTextWithHint("password (w/ hint)", "<password>", password, IM_ARRAYSIZE(password), ImGuiInputTextFlags_Password | ImGuiInputTextFlags_CharsNoBlank);
+            ImGui::InputText("password (clear)", password, IM_ARRAYSIZE(password), ImGuiInputTextFlags_CharsNoBlank);
             ImGui::TreePop();
         }
 
@@ -3465,6 +3465,7 @@ void ImGui::ShowStyleEditor(ImGuiStyle* ref)
                                         ImGui::BeginTooltip();
                                         ImGui::Text("Codepoint: U+%04X", base + n);
                                         ImGui::Separator();
+                                        ImGui::Text("Visible: %d", glyph->Visible);
                                         ImGui::Text("AdvanceX: %.1f", glyph->AdvanceX);
                                         ImGui::Text("Pos: (%.2f,%.2f)->(%.2f,%.2f)", glyph->X0, glyph->Y0, glyph->X1, glyph->Y1);
                                         ImGui::Text("UV: (%.3f,%.3f)->(%.3f,%.3f)", glyph->U0, glyph->V0, glyph->U1, glyph->V1);

imgui_draw.cpp

@@ -2622,6 +2622,7 @@ void ImFont::BuildLookupTable()
     for (int i = 0; i != Glyphs.Size; i++)
         max_codepoint = ImMax(max_codepoint, (int)Glyphs[i].Codepoint);
 
+    // Build lookup table
     IM_ASSERT(Glyphs.Size < 0xFFFF); // -1 is reserved
     IndexAdvanceX.clear();
     IndexLookup.clear();
@@ -2638,7 +2639,7 @@ void ImFont::BuildLookupTable()
     // FIXME: Needs proper TAB handling but it needs to be contextualized (or we could arbitrary say that each string starts at "column 0" ?)
     if (FindGlyph((ImWchar)' '))
     {
-        if (Glyphs.back().Codepoint != '\t')   // So we can call this function multiple times
+        if (Glyphs.back().Codepoint != '\t')   // So we can call this function multiple times (FIXME: Flaky)
             Glyphs.resize(Glyphs.Size + 1);
         ImFontGlyph& tab_glyph = Glyphs.back();
         tab_glyph = *FindGlyph((ImWchar)' ');
@@ -2648,6 +2649,11 @@ void ImFont::BuildLookupTable()
         IndexLookup[(int)tab_glyph.Codepoint] = (ImWchar)(Glyphs.Size-1);
     }
 
+    // Mark special glyphs as not visible (note that AddGlyph already mark as non-visible glyphs with zero-size polygons)
+    SetGlyphVisible((ImWchar)' ', false);
+    SetGlyphVisible((ImWchar)'\t', false);
+
+    // Setup fall-backs
     FallbackGlyph = FindGlyphNoFallback(FallbackChar);
     FallbackAdvanceX = FallbackGlyph ? FallbackGlyph->AdvanceX : 0.0f;
     for (int i = 0; i < max_codepoint + 1; i++)
@@ -2655,6 +2661,12 @@ void ImFont::BuildLookupTable()
             IndexAdvanceX[i] = FallbackAdvanceX;
 }
 
+void ImFont::SetGlyphVisible(ImWchar c, bool visible)
+{
+    if (ImFontGlyph* glyph = (ImFontGlyph*)(void*)FindGlyph((ImWchar)c))
+        glyph->Visible = visible ? 1 : 0;
+}
+
 void ImFont::SetFallbackChar(ImWchar c)
 {
     FallbackChar = c;
@@ -2676,7 +2688,8 @@ void ImFont::AddGlyph(ImWchar codepoint, float x0, float y0, float x1, float y1,
 {
     Glyphs.resize(Glyphs.Size + 1);
     ImFontGlyph& glyph = Glyphs.back();
-    glyph.Codepoint = (ImWchar)codepoint;
+    glyph.Codepoint = (unsigned int)codepoint;
+    glyph.Visible = (x0 != x1) && (y0 != y1);
     glyph.X0 = x0;
     glyph.Y0 = y0;
     glyph.X1 = x1;
@@ -2925,17 +2938,15 @@ ImVec2 ImFont::CalcTextSizeA(float size, float max_width, float wrap_width, cons
 
 void ImFont::RenderChar(ImDrawList* draw_list, float size, ImVec2 pos, ImU32 col, ImWchar c) const
 {
-    if (c == ' ' || c == '\t' || c == '\n' || c == '\r') // Match behavior of RenderText(), those 4 codepoints are hard-coded.
+    const ImFontGlyph* glyph = FindGlyph(c);
+    if (!glyph || !glyph->Visible)
         return;
-    if (const ImFontGlyph* glyph = FindGlyph(c))
-    {
     float scale = (size >= 0.0f) ? (size / FontSize) : 1.0f;
     pos.x = IM_FLOOR(pos.x + DisplayOffset.x);
     pos.y = IM_FLOOR(pos.y + DisplayOffset.y);
     draw_list->PrimReserve(6, 4);
     draw_list->PrimRectUV(ImVec2(pos.x + glyph->X0 * scale, pos.y + glyph->Y0 * scale), ImVec2(pos.x + glyph->X1 * scale, pos.y + glyph->Y1 * scale), ImVec2(glyph->U0, glyph->V0), ImVec2(glyph->U1, glyph->V1), col);
 }
-}
 
 void ImFont::RenderText(ImDrawList* draw_list, float size, ImVec2 pos, ImU32 col, const ImVec4& clip_rect, const char* text_begin, const char* text_end, float wrap_width, bool cpu_fine_clip) const
 {
@@ -3047,13 +3058,12 @@ void ImFont::RenderText(ImDrawList* draw_list, float size, ImVec2 pos, ImU32 col
                 continue;
         }
 
-        float char_width = 0.0f;
-        if (const ImFontGlyph* glyph = FindGlyph((ImWchar)c))
-        {
-            char_width = glyph->AdvanceX * scale;
+        const ImFontGlyph* glyph = FindGlyph((ImWchar)c);
+        if (glyph == NULL)
+            continue;
 
-            // Arbitrarily assume that both space and tabs are empty glyphs as an optimization
-            if (c != ' ' && c != '\t')
+        float char_width = glyph->AdvanceX * scale;
+        if (glyph->Visible)
         {
             // We don't do a second finer clipping test on the Y axis as we've already skipped anything before clip_rect.y and exit once we pass clip_rect.w
             float x1 = x + glyph->X0 * scale;
@@ -3112,8 +3122,6 @@ void ImFont::RenderText(ImDrawList* draw_list, float size, ImVec2 pos, ImU32 col
                 }
             }
         }
-        }
-
         x += char_width;
     }