tflatlistboxunit.pas

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  canvas.Brush.Color := Color;
  canvas.FillRect(Rect(ClientRect.Left, ClientRect.Top, ClientRect.Right, ClientRect.Top + 11));
  canvas.FillRect(Rect(ClientRect.Left, ClientRect.Bottom - 11, ClientRect.Right, ClientRect.Bottom));

  // Draw the ScrollBar border
  canvas.Brush.Color := FBorderColor;
  canvas.FrameRect(Rect(ClientRect.Left, ClientRect.Top, ClientRect.Right, ClientRect.Top + 11));
  canvas.FrameRect(Rect(ClientRect.Left, ClientRect.Bottom - 11, ClientRect.Right, ClientRect.Bottom));

  // Draw the up arrow
  x := (ClientRect.Right - ClientRect.Left) div 2 - 6;
  y := ClientRect.Top + 4;

  if (firstItem <> 0) and Enabled then
  begin
    canvas.Brush.Color := FArrowColor;
    canvas.Pen.Color := FArrowColor;
    canvas.Polygon([Point(x + 4, y + 2), Point(x + 8, y + 2), Point(x + 6, y)]);
  end
  else
  begin
    canvas.Brush.Color := clWhite;
    canvas.Pen.Color := clWhite;
    Inc(x); Inc(y);
    canvas.Polygon([Point(x + 4, y + 2), Point(x + 8, y + 2), Point(x + 6, y)]);
    Dec(x); Dec(y);
    canvas.Brush.Color := clGray;
    canvas.Pen.Color := clGray;
    canvas.Polygon([Point(x + 4, y + 2), Point(x + 8, y + 2), Point(x + 6, y)]);
  end;

  // Draw the down arrow
  y := ClientRect.Bottom - 7;
  if (firstItem + maxItems + 1 <= FItems.Count) and Enabled then
  begin
    canvas.Brush.Color := FArrowColor;
    canvas.Pen.Color := FArrowColor;
    canvas.Polygon([Point(X + 4, Y), Point(X + 8, Y), Point(X + 6, Y + 2)]);
  end
  else
  begin
    canvas.Brush.Color := clWhite;
    canvas.Pen.Color := clWhite;
    Inc(x); Inc(y);
    canvas.Polygon([Point(X + 4, Y), Point(X + 8, Y), Point(X + 6, Y + 2)]);
    Dec(x); Dec(y);
    canvas.Brush.Color := clGray;
    canvas.Pen.Color := clGray;
    canvas.Polygon([Point(X + 4, Y), Point(X + 8, Y), Point(X + 6, Y + 2)]);
  end;
end;

procedure TFlatListBox.Paint;
var
  memoryBitmap: TBitmap;
  counterRect, counterItem: Integer;
  itemRect: ^TRect;
  Format: UINT;
begin
  {$IFDEF DFS_COMPILER_4_UP}
  if BidiMode = bdRightToLeft then
    Format := DT_RIGHT or DT_VCENTER or DT_SINGLELINE or DT_NOPREFIX
  else
    Format := DT_LEFT or DT_VCENTER or DT_SINGLELINE or DT_NOPREFIX;
  {$ELSE}
  Format := DT_LEFT or DT_VCENTER or DT_SINGLELINE or DT_NOPREFIX;
  {$ENDIF}

  // create memory-bitmap to draw flicker-free
  memoryBitmap := TBitmap.Create;
  try
    memoryBitmap.Height := ClientRect.Bottom;
    memoryBitmap.Width := ClientRect.Right;
    memoryBitmap.Canvas.Font.Assign(Self.Font);

    // Clear Background
    case FTransparent of
      tmAlways:
        DrawParentImage(Self, memoryBitmap.Canvas);
      tmNone:
        begin
          memoryBitmap.canvas.Brush.Color := FItemsRectColor;
          memoryBitmap.canvas.FillRect(ClientRect);
        end;
      tmNotFocused:
        if Focused then
        begin
          memoryBitmap.canvas.Brush.Color := FItemsRectColor;
          memoryBitmap.canvas.FillRect(ClientRect);
        end
        else
          DrawParentImage(Self, memoryBitmap.Canvas);
    end;

    // Draw Border
    memoryBitmap.canvas.Brush.Color := FBorderColor;
    memoryBitmap.canvas.FrameRect(ClientRect);

    // Draw ScrollBars
    if ScrollBars then
      DrawScrollBar(memoryBitmap.canvas);

    // Initialize the counter for the Items
    counterItem := firstItem;

    // Draw Items
    for counterRect := 0 to maxItems - 1 do
    begin
      itemRect := FItemsRect.Items[counterRect];
      if (counterItem <= FItems.Count - 1) then
      begin
        // Item is selected
        if counterItem in FSelected then
        begin
          // Fill ItemRect
          memoryBitmap.canvas.brush.color := FItemsSelectColor;
          memoryBitmap.canvas.FillRect(itemRect^);
          // Draw ItemBorder
          memoryBitmap.canvas.brush.color := FBorderColor;
          memoryBitmap.canvas.FrameRect(itemRect^);
        end;
        // Draw ItemText
        memoryBitmap.canvas.brush.style := bsClear;
        InflateRect(itemRect^, -3, 0);
        if Enabled then
          DrawText(memoryBitmap.canvas.Handle, PChar(FItems[counterItem]), Length(FItems[counterItem]), itemRect^, Format)
        else
          begin
            OffsetRect(itemRect^, 1, 1);
            memoryBitmap.canvas.Font.Color := clBtnHighlight;
            DrawText(memoryBitmap.canvas.Handle, PChar(FItems[counterItem]), Length(FItems[counterItem]), itemRect^, Format);
            OffsetRect(itemRect^, -1, -1);
            memoryBitmap.canvas.Font.Color := clBtnShadow;
            DrawText(memoryBitmap.canvas.Handle, PChar(FItems[counterItem]), Length(FItems[counterItem]), itemRect^, Format);
          end;
        InflateRect(itemRect^, 3, 0);
        Inc(counterItem);
      end;
    end;
    // Copy bitmap to screen
    canvas.CopyRect(ClientRect, memoryBitmap.canvas, ClientRect);
  finally
    // delete the memory bitmap
    memoryBitmap.free;
  end;
end;

procedure TFlatListBox.MouseDown (Button: TMouseButton; Shift: TShiftState; X, Y: Integer);
var
  cursorPos: TPoint;
  counterRect: Integer;
  currentRect: ^TRect;
begin
  GetCursorPos(cursorPos);
  cursorPos := ScreenToClient(cursorPos);

  if (FItems.Count > 0) and (Button = mbLeft) then
  begin
    for counterRect := 0 to FItemsRect.Count - 1 do
    begin
      currentRect := FItemsRect.Items[counterRect];
      if PtInRect(currentRect^, cursorPos) then
      begin
        if MultiSelect then
        begin
          if (firstItem + counterRect) in FSelected then
            Exclude(FSelected, firstItem + counterRect)
          else
            Include(FSelected, firstItem + counterRect);
          FItemIndex := firstItem + counterRect;
        end
        else
        begin
          FSelected := FSelected - [0..High(Byte)];
          Include(FSelected, firstItem + counterRect);
          FItemIndex := firstItem + counterRect;
        end;
        SetFocus;
        Invalidate;
        Exit;
      end;
    end;
  end;

  if ScrollBars then
  begin
    if PtInRect(Rect(ClientRect.Left, ClientRect.Top, ClientRect.Right, ClientRect.Top + 11), cursorPos) then
    begin
      if (firstItem - 1) < 0 then
        firstItem := 0
      else
        Dec(firstItem);
      SetFocus;
      Invalidate;
      scrollType := up;
      if ScrollTimer.Enabled then
        ScrollTimer.Enabled := False;
      ScrollTimer.OnTimer := ScrollTimerHandler;
      ScrollTimer.Enabled := True;
    end;
    if PtInRect(Rect(ClientRect.Left, ClientRect.Bottom - 11, ClientRect.Right, ClientRect.Bottom), cursorPos) then
    begin
      if firstItem + maxItems + 1 <= FItems.Count then
        Inc(firstItem);
      SetFocus;
      Invalidate;
      scrollType := down;
      if ScrollTimer.Enabled then
        ScrollTimer.Enabled := False;
      ScrollTimer.OnTimer := ScrollTimerHandler;
      ScrollTimer.Enabled := True;
    end;
  end;
  Inherited;
end;

procedure TFlatListBox.MouseUp (Button: TMouseButton; Shift: TShiftState; X, Y: Integer);
begin
  ScrollTimer.Enabled := False;
  ScrollTimer.Interval := FTimerInterval;
  inherited MouseUp(Button, Shift, X, Y);
end;

procedure TFlatListBox.ScrollTimerHandler (Sender: TObject);
begin
  ScrollTimer.Interval := FScrollSpeed;
  if scrollType = up then
    if (firstItem - 1) < 0 then
    begin
      firstItem := 0;
      ScrollTimer.Enabled := False;
    end
    else
      Dec(firstItem)
  else
    if firstItem + maxItems + 1 <= FItems.Count then
      Inc(firstItem)
    else
      ScrollTimer.Enabled := False;
  Invalidate;
end;

procedure TFlatListBox.Loaded;
begin
  inherited;
  SetItemsRect;
end;

procedure TFlatListBox.WMSize (var Message: TWMSize);
begin
  inherited;
  // Calculate the maximum items to draw
  if ScrollBars then
    maxItems := (Height - 24) div (FItemsHeight + 2)
  else
    maxItems := (Height - 4) div (FItemsHeight + 2);

  // Set the new Bounds
  if ScrollBars then
    SetBounds(Left, Top, Width, maxItems * (FItemsHeight + 2) + 24)
  else
    SetBounds(Left, Top, Width, maxItems * (FItemsHeight + 2) + 4);

  // Recalculate the itemRects
  SetItemsRect;
end;

procedure TFlatListBox.CMEnabledChanged (var Message: TMessage);
begin
  inherited;
  Invalidate;
end;

procedure TFlatListBox.CMSysColorChange (var Message: TMessage);
begin
  if FUseAdvColors then
  begin
    ParentColor := True;
    CalcAdvColors;
  end;
  Invalidate;
end;

procedure TFlatListBox.CMParentColorChanged (var Message: TWMNoParams);
begin
  inherited;
  if FUseAdvColors then
  begin
    ParentColor := True;
    CalcAdvColors;
  end;
  Invalidate;
end;

procedure TFlatListBox.SetTransparent (const Value: TTransparentMode);
begin
  FTransparent := Value;
  Invalidate;
end;

procedure TFlatListBox.WMMove (var Message: TWMMove);
begin
  inherited;
  if not (FTransparent = tmNone) then
    Invalidate;
end;

procedure TFlatListBox.WMKillFocus (var Message: TWMKillFocus);
begin
  inherited;
  if not (FTransparent = tmNone) then
    Invalidate;
end;

procedure TFlatListBox.WMSetFocus (var Message: TWMSetFocus);
begin
  inherited;
  if not (FTransparent = tmNone) then
    Invalidate;
end;

procedure TFlatListBox.CNKeyDown (var Message: TWMKeyDown);
begin
  case Message.CharCode of
    VK_UP:
      if (firstItem - 1) < 0 then
        firstItem := 0
      else
        Dec(firstItem);
    VK_DOWN:
      if firstItem + maxItems + 1 <= FItems.Count then
        Inc(firstItem);
    VK_PRIOR:
      if (firstItem - maxItems) < 0 then
        firstItem := 0
      else
        Dec(firstItem, maxItems);
    VK_NEXT:
      if firstItem + (maxItems * 2) <= FItems.Count then
        Inc(firstItem, maxItems)
      else
        firstItem := FItems.Count - maxItems;
  else
    inherited;
  end;
  Invalidate;
end;

function TFlatListBox.GetItemIndex: Integer;
begin
  Result := FItemIndex;
end;

procedure TFlatListBox.SetItemIndex (Value: Integer);
begin
  if GetItemIndex <> Value then
  begin
    FItemIndex := Value;
    if MultiSelect then
    begin
      if (Value) in FSelected then
        Exclude(FSelected, Value)
      else
        Include(FSelected, Value);
    end
    else
    begin
      FSelected := FSelected - [0..High(Byte)];
      Include(FSelected, Value);
    end;
    Invalidate;
  end;
end;

procedure TFlatListBox.SetMultiSelect (Value: Boolean);
begin
  FMultiSelect := Value;
  if Value then
    FItemIndex := 0;
end;

{$IFDEF DFS_COMPILER_4_UP}
procedure TFlatListBox.SetBiDiMode(Value: TBiDiMode);
begin
  inherited;
  Invalidate;
end;
{$ENDIF}

end.