What is carat? How we use it?

Text Caret

Caret is a blinking cursor in a window. It displays the current position of the cursor where the input is getting added from user. A textbox or text area control automatically displayes caret. It is the builtin property of the windon. However a custom window application which displayes logs, terminal or console output etc can use caret. Win32 APIs are available to create, distroy, show, hide, set position etc.

CreateCare

CreateCaret() creates a cursor with a size of nWidth x nHeight. It creates a solid cursor if hBitmap is NULL else the bitmap is used for drawing the cursor.

BOOL WINAPI CreateCaret(HWND hWnd, HBITMAP hBitmap, int nWidth, int nHeight);

DestroyCaret

Frees the memory of cursor object and releases the handle

BOOL WINAPI DestroyCaret(void);

GetCaretBlinkTime

Returns the current blink interval time of the cursor in milliseconds. The less the number the more the blink rate.

UINT WINAPI GetCaretBlinkTime(void);

GetCaretPos

Returns the current position of the cursor.

BOOL WINAPI GetCaretPos(LPPOINT lpPoint);

HideCaret

Hides the cursor of the window.

BOOL WINAPI HideCaret(HWND hWnd);

SetCaretBlinkTime

Set the blink time of the caret in miliseconds. The less the time the more the blinking rate.

BOOL WINAPI SetCaretBlinkTime(UINT uMSeconds);

SetCaretPos

SetCaretPos set the caret position in the window

BOOL WINAPI SetCaretPos(int X, int Y);

ShowCaret

ShowCaret shows the blinking caret

BOOL WINAPI ShowCaret(HWND hWnd);

Caret Demo application

Demo aplication showing Create, Destroy, Show, Hide of Caret/Cursor. With UP arrow key, caret blink time is reduced and blink rate increases. With DOWN arrow key, caret blink time is increated and blink rate reduced.

 unsigned int nBlinkRate;

 LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)

 {

   CHAR szTitle[100];

   switch (message) 

   {

     case WM_KEYDOWN:

             if(wParam == VK_UP)

       {

               nBlinkRate-=10;

         SetCaretBlinkTime(nBlinkRate);

         sprintf(szTitle,"Cursor blink rate %d", nBlinkRate);

         SetWindowText(hWnd,szTitle);

       }

             else if(wParam == VK_DOWN)

       {

         nBlinkRate+=10;

         SetCaretBlinkTime(nBlinkRate);

         sprintf(szTitle,"Cursor blink rate %d", nBlinkRate);

         SetWindowText(hWnd,szTitle);

       }

       break;

     case WM_DESTROY:

       PostQuitMessage(0);

       break;

     case WM_SETFOCUS:

         CreateCaret(hWnd, NULL, 12,2);

       SetCaretPos(0,16);

       ShowCaret(hWnd);

       nBlinkRate = GetCaretBlinkTime();

       sprintf(szTitle,"Cursor blink rate %d", nBlinkRate);

         SetWindowText(hWnd,szTitle);

       break;

     case WM_KILLFOCUS:

       HideCaret(hWnd);

       DestroyCaret();

       break;

     default:

       return DefWindowProc(hWnd, message, wParam, lParam);

    }

    return 0;

 }

Output

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