platform: fix initial cursor size on Windows

6c0745c introduced the assumption in BufferedDisplay that the cursor is initially hidden, but this is not true on Windows.

A possible solution is to do something similar to what we did for the screen size: we store in DisplayStrategy a variable that represents the actual cursor size, and update it in DisplayStrategy::reloadScreenInfo(). BufferedDisplay now stores the 'future' cursor size instead of the 'last' one.

The only difference between this solution and the one for screen size is that while DisplayStrategy::size is modified exclusively from DisplayStrategy::reloadScreenInfo(), DisplayStrategy::caretSize is also modified from BufferedDisplay::flushScreen(), because flushScreen() does change the terminal's cursor size.

include/tvision/internal/buffdisp.h

@@ -14,23 +14,6 @@ class ScreenCursor;
 
 class BufferedDisplay : public DisplayStrategy {
 
-protected:
-
-    // 'caretSize' must be a value in the range 0 to 100. Zero means it is not
-    // visible.
-
-    int caretSize;
-
-    // 'getCaretSize()' must return a number in the range 1 to 100,
-    // because the original THardwareInfo interface maps directly to
-    // the Win32 Console API (see CONSOLE_CURSOR_INFO).
-
-    int getCaretSize() override { return max(caretSize, 1); }
-    bool isCaretVisible() override { return caretSize > 0; }
-    void setCaretSize(int size) override { caretSize = size; }
-
-private:
-
     friend struct FlushScreenAlgorithm;
 
     struct Range {
@@ -45,7 +28,7 @@ class BufferedDisplay : public DisplayStrategy {
     const uint widePlaceholder;
     bool caretMoved;
     TPoint caretPosition;
-    int lastCaretSize;
+    int newCaretSize;
 
     bool limitFPS;
     int frameDrops;
@@ -81,7 +64,8 @@ class BufferedDisplay : public DisplayStrategy {
     BufferedDisplay();
     ~BufferedDisplay();
 
-    void setCaretPosition(int x, int y);
+    void setCaretSize(int size) override;
+    void setCaretPosition(int x, int y) override;
     void screenWrite(int x, int y, TScreenCell *buf, int len) override;
     void flushScreen() override;
     void reloadScreenInfo() override;

include/tvision/internal/platform.h

@@ -15,24 +15,37 @@ class DisplayStrategy {
 
     virtual ~DisplayStrategy() {}
 
-    // 'size' must not change until 'reloadScreenInfo()' is invoked.
-    // Invariant: 'size' is in sync with the actual screen size after
-    // 'DisplayStrategy::reloadScreenInfo()' has been invoked.
+    // Invariant: these variables are is in sync with the actual screen state
+    // after 'DisplayStrategy::reloadScreenInfo()' has been invoked.
 
     TPoint size {};
+    int caretSize {};
 
     // This function can be overriden by inheritors in order to update
-    // internal structs when the display properties change.
+    // internal structs when the display properties change. But
+    // 'DisplayStrategy::reloadScreenInfo()' must be invoked eventually.
 
-    virtual void reloadScreenInfo() { size = getScreenSize(); };
+    virtual void reloadScreenInfo()
+    {
+        size = getScreenSize();
+        caretSize = getCaretSize();
+    }
+
+protected:
 
-    // The function is meant to be overriden by inheritors. Its only
-    // responsibility should be to return the updated screen size.
+    // These functions are meant to be overriden by inheritors. Their only
+    // responsibility should be to return updated values.
 
     virtual TPoint getScreenSize() { return size; }
 
-    virtual int getCaretSize() { return 0; }
-    virtual bool isCaretVisible() { return false; }
+    // 'getCaretSize()' must return a value in the range 0 to 100. Zero means
+    // the caret is not visible.
+
+    virtual int getCaretSize() { return caretSize; }
+
+public:
+
+    bool isCaretVisible() { return caretSize != 0; }
     virtual void clearScreen() {}
     virtual void setCaretPosition(int x, int y) {}
     virtual ushort getScreenMode() { return 0; }
@@ -79,7 +92,7 @@ class PlatformStrategy {
     virtual void cursorOn() { if (input) input->cursorOn(); }
     virtual void cursorOff() { if (input) input->cursorOff(); }
 
-    virtual int getCaretSize() { return display->getCaretSize(); }
+    virtual int getCaretSize() { return display->caretSize; }
     virtual bool isCaretVisible() { return display->isCaretVisible(); }
     virtual void clearScreen() { display->clearScreen(); }
     virtual int getScreenRows() { return display->size.y; }

include/tvision/internal/win32con.h

@@ -93,6 +93,7 @@ class Win32Display : public BufferedDisplay
 
     void reloadScreenInfo() override;
     TPoint getScreenSize() override;
+    int getCaretSize() override;
 
     void clearScreen() override;
     ushort getScreenMode() override;

source/platform/buffdisp.cpp

@@ -38,7 +38,7 @@ BufferedDisplay::BufferedDisplay() :
     screenChanged = true;
     caretMoved = false;
     caretPosition = {-1, -1};
-    caretSize = lastCaretSize = 0;
+    newCaretSize = 0;
 }
 
 BufferedDisplay::~BufferedDisplay()
@@ -61,6 +61,11 @@ void BufferedDisplay::resizeBuffer()
     rowDamage.resize(size.y, {INT_MAX, INT_MIN});
 }
 
+void BufferedDisplay::setCaretSize(int size)
+{
+    newCaretSize = size;
+}
+
 void BufferedDisplay::setCaretPosition(int x, int y)
 {
     caretPosition = {x, y};
@@ -156,7 +161,7 @@ void BufferedDisplay::undrawCursors()
 
 bool BufferedDisplay::needsFlush() const
 {
-    return screenChanged || caretMoved || caretSize != lastCaretSize;
+    return screenChanged || caretMoved || caretSize != newCaretSize;
 }
 
 void BufferedDisplay::flushScreen()
@@ -168,12 +173,12 @@ void BufferedDisplay::flushScreen()
         if (caretPosition.x != -1)
             lowlevelMoveCursor(caretPosition.x, caretPosition.y);
         undrawCursors();
-        if (caretSize != lastCaretSize)
-            lowlevelCursorSize(caretSize);
+        if (caretSize != newCaretSize)
+            lowlevelCursorSize(newCaretSize);
         lowlevelFlush();
         screenChanged = false;
         caretMoved = false;
-        lastCaretSize = caretSize;
+        caretSize = newCaretSize;
     }
 }
 

source/platform/win32con.cpp

@@ -292,9 +292,6 @@ Win32Display::Win32Display(Win32ConsoleStrategy &cnState) :
     cnState(cnState),
     lastAttr('\x00')
 {
-    CONSOLE_CURSOR_INFO crInfo {};
-    GetConsoleCursorInfo(cnHandle(), &crInfo);
-    setCaretSize(crInfo.bVisible ? crInfo.dwSize : 0);
 }
 
 void Win32Display::reloadScreenInfo()
@@ -308,6 +305,13 @@ TPoint Win32Display::getScreenSize()
     return {cnState.sbInfo.dwSize.X, cnState.sbInfo.dwSize.Y};
 }
 
+int Win32Display::getCaretSize()
+{
+    CONSOLE_CURSOR_INFO crInfo {};
+    GetConsoleCursorInfo(cnHandle(), &crInfo);
+    return crInfo.bVisible ? crInfo.dwSize : 0;
+}
+
 void Win32Display::lowlevelCursorSize(int size)
 {
     CONSOLE_CURSOR_INFO crInfo;