Preserve selected and reverse-video text colors beneath a block cursor

bin/st/shitty.toml

@@ -47,6 +47,9 @@ border = 2
 # CLI: -cr COLOR — Set the cursor RGB color; omit the key to use the foreground color.
 cr = "#88c0d0"
 
+# CLI: -cursorKeepSelectionFg / +cursorKeepSelectionFg — Keep selected or reverse-video text's foreground color under the block cursor.
+cursorKeepSelectionFg = false
+
 # CLI: -dump PATH — Write raw PTY input to PATH; normally omitted.
 # dump = "/tmp/shitty.pty"
 

lib/shitty/options.cpp

@@ -89,6 +89,7 @@ namespace {
         {"config", OptionKind::SepArg, nullptr, nullptr, "Path to the TOML config file", true},
         {"colorScheme", OptionKind::SepArg, nullptr, "default", "Named terminal color scheme"},
         {"cr", OptionKind::SepArg, nullptr, nullptr, "Cursor color"},
+        {"cursorKeepSelectionFg", OptionKind::NoArg, "true", "false", "Keep selected or reverse-video text color under the block cursor"},
         {"debug", OptionKind::SepArg, nullptr, nullptr, "Append window, font and grid diagnostics to this file", true},
         {"dump", OptionKind::SepArg, nullptr, nullptr, "Dump raw PTY input to file"},
         {"fg", OptionKind::SepArg, nullptr, "#fff", "Foreground color"},
@@ -1276,6 +1277,7 @@ void OptionsParser::parse() {
         maximized = getBool("maximized");
         fullscreen = getBool("fullscreen");
         showWraps = getBool("showWraps");
+        cursorKeepSelectionFg = getBool("cursorKeepSelectionFg");
         vt.verbose = getBool("verbose");
         vt.modifyOtherKeys = getInteger("modifyOtherKeys", 0, 2);
     } catch (Exception& error) {

lib/shitty/options.h

@@ -99,6 +99,7 @@ struct Options {
     bool titleFallbackProcess = false;
     bool optical = false;
     bool showWraps = false;
+    bool cursorKeepSelectionFg = false;
     bool rv = false;
 
     static Options* create(stl::ObjPool& pool, Brand& brand, char** argv, int argc, OptionsLoad load = OptionsLoad::Startup);

lib/shitty/options_ut.cpp

@@ -41,6 +41,19 @@ namespace {
 }
 
 STD_TEST_SUITE(Options) {
+    STD_TEST(CursorKeepSelectionFgFlag) {
+        auto pool = ObjPool::fromMemory();
+        char program[] = "st";
+        char enabled[] = "-cursorKeepSelectionFg";
+        char disabled[] = "+cursorKeepSelectionFg";
+        char* defaults[] = {program, nullptr};
+        char* on[] = {program, enabled, nullptr};
+        char* off[] = {program, enabled, disabled, nullptr};
+        STD_INSIST(!Options::create(*pool, *Brand::generic(), defaults, 1)->cursorKeepSelectionFg);
+        STD_INSIST(Options::create(*pool, *Brand::generic(), on, 2)->cursorKeepSelectionFg);
+        STD_INSIST(!Options::create(*pool, *Brand::generic(), off, 3)->cursorKeepSelectionFg);
+    }
+
     STD_TEST(SymbolFontTablesParseFromConfig) {
         auto pool = ObjPool::fromMemory();
         Buffer config = writeTempConfig(StringView(

lib/shitty/render.comp

@@ -77,6 +77,7 @@ layout (push_constant) uniform PushConstants
    uint hoveredLinkBegin;
    uint hoveredLinkEnd;
    uint updateCount;
+   uint cursorKeepSelectionFg;
 } parameters;
 
 vec3 unpackColor (uint color)
@@ -592,7 +593,8 @@ void main ()
       foreground = background;
       background = temporary;
    }
-   if (selected (cellPosition, doubleWidth))
+   bool selectedCell = selected (cellPosition, doubleWidth);
+   if (selectedCell)
    {
       if (parameters.selectionColorMask == 0)
       {
@@ -633,7 +635,8 @@ void main ()
       (parameters.cursorBlink == 0 || parameters.blinkVisible != 0);
    if (cursorHere && parameters.cursorStyle == 1)
    {
-      foreground = background;
+      if (!(selectedCell || inverse != 0) || parameters.cursorKeepSelectionFg == 0)
+         foreground = background;
       background = cursor;
    }
 

lib/shitty/render_metal.mm

@@ -124,9 +124,10 @@
         u32 hoveredLinkBegin;
         u32 hoveredLinkEnd;
         u32 updateCount;
+        u32 cursorKeepSelectionFg;
     };
 
-    static_assert(sizeof(PushConstants) == 116, "Metal push constant layout mismatch");
+    static_assert(sizeof(PushConstants) == 120, "Metal push constant layout mismatch");
 
     struct PresentationState {
         TerminalCursor cursor;
@@ -694,6 +695,7 @@
         state.hoveredLinkBegin,
         state.hoveredLinkEnd,
         updateCount,
+        composer.opts->cursorKeepSelectionFg ? 1u : 0u,
     };
 
     // The spirv-cross assignment for this shader: push constants at

lib/shitty/render_reference.cpp

@@ -423,7 +423,8 @@ void ReferenceRendererImpl::renderCell(const TerminalUpdate& update, const Refer
     if ((source.inverse != 0) != update.screenReverse) {
         xchg(foreground, background);
     }
-    if (selected(update, source, column, row)) {
+    const bool selectedCell = selected(update, source, column, row);
+    if (selectedCell) {
         if (update.selectionColorMask == 0) {
             xchg(foreground, background);
         } else {
@@ -448,7 +449,9 @@ void ReferenceRendererImpl::renderCell(const TerminalUpdate& update, const Refer
     }
     const bool cursorHere = column == update.cursor.posX && row == update.cursor.posY && (!update.cursorBlink || update.blinkVisible);
     if (cursorHere && update.cursor.style == TerminalCursor::Style::filled_block) {
-        foreground = background;
+        if (!(selectedCell || source.inverse) || !composer_.opts->cursorKeepSelectionFg) {
+            foreground = background;
+        }
         background = cursor;
     }
 

lib/shitty/render_reference_ut.cpp

@@ -331,6 +331,63 @@ STD_TEST_SUITE(ReferenceRenderer) {
         STD_INSIST((cellPixel(image, 1, 0) == Color{4, 5, 6}));
     }
 
+    STD_TEST(CursorKeepsSelectedForegroundWhenEnabled) {
+        ScreenFixture fx(1, 1);
+        TerminalCell attrs = coloredCell({255, 0, 0}, {0, 0, 255});
+        // An overline gives exact foreground pixels without glyph antialiasing.
+        attrs.overline = true;
+        fx.writeText(0, 0, " ", attrs);
+        Options options;
+        fx.composer->setOptions(&options);
+        ReferenceFixture renderer(*fx.composer);
+        TerminalUpdate update = fx.capture();
+        update.snappedSelection = Rect(0, 0);
+        update.cursor.color = {0, 255, 0};
+        update.cursor.style = TerminalCursor::Style::filled_block;
+        const auto checkColors = [&](Color foreground) {
+            const ReferenceImage image = renderer->render(update);
+            STD_INSIST(image.pixels != nullptr);
+            STD_INSIST(cellPixel(image, 0, 0) == foreground);
+            STD_INSIST(cellPixel(image, 0, 1) == update.cursor.color);
+        };
+
+        checkColors({255, 0, 0});
+        options.cursorKeepSelectionFg = true;
+        checkColors({0, 0, 255});
+        update.snappedSelection = {};
+        checkColors({0, 0, 255});
+    }
+
+    STD_TEST(CursorKeepsReverseVideoForegroundWhenEnabled) {
+        ScreenFixture fx(1, 1);
+        TerminalCell attrs = coloredCell({255, 0, 0}, {0, 0, 255});
+        attrs.inverse = true;
+        attrs.overline = true;
+        fx.writeText(0, 0, " ", attrs);
+        Options options;
+        fx.composer->setOptions(&options);
+        ReferenceFixture renderer(*fx.composer);
+        TerminalUpdate update = fx.capture();
+        update.cursor.color = {0, 255, 0};
+        update.cursor.style = TerminalCursor::Style::filled_block;
+        const auto checkColors = [&](Color foreground) {
+            const ReferenceImage image = renderer->render(update);
+            STD_INSIST(image.pixels != nullptr);
+            STD_INSIST(cellPixel(image, 0, 0) == foreground);
+            STD_INSIST(cellPixel(image, 0, 1) == update.cursor.color);
+        };
+
+        checkColors({255, 0, 0});
+        options.cursorKeepSelectionFg = true;
+        checkColors({0, 0, 255});
+        attrs.inverse = false;
+        fx.writeText(0, 0, " ", attrs);
+        update = fx.capture();
+        update.cursor.color = {0, 255, 0};
+        update.cursor.style = TerminalCursor::Style::filled_block;
+        checkColors({0, 0, 255});
+    }
+
     STD_TEST(SelectionOfWideContinuationHighlightsWholeGlyph) {
         auto pool = ObjPool::fromMemory();
         Composer& composer = *pool->make<Composer>(pool.mutPtr());

lib/shitty/render_vk.cpp

@@ -172,9 +172,10 @@ namespace {
             u32 hoveredLinkBegin;
             u32 hoveredLinkEnd;
             u32 updateCount;
+            u32 cursorKeepSelectionFg;
         };
 
-        static_assert(sizeof(PushConstants) == 116, "Vulkan push constant layout mismatch");
+        static_assert(sizeof(PushConstants) == 120, "Vulkan push constant layout mismatch");
 
         // The strip arenas mirrored on the device; append-only between
         // collections, so only the tail uploads each frame.
@@ -1793,6 +1794,7 @@ void RendererImpl::recordCommands(FrameResources& frame, u32 imageIndex, const P
             state.hoveredLinkBegin,
             state.hoveredLinkEnd,
             updateCount,
+            composer.opts->cursorKeepSelectionFg ? 1u : 0u,
         };
         vkCmdBindPipeline(frame.commandBuffer, VK_PIPELINE_BIND_POINT_COMPUTE, pipeline);
         vkCmdBindDescriptorSets(frame.commandBuffer, VK_PIPELINE_BIND_POINT_COMPUTE, pipelineLayout, 0, 1, &frame.descriptorSet, 0, nullptr);