Rapid-Q Documentation by William Yu (c)1999-2000 Appendix A: QCANVAS

QCANVAS Component

QCanvas is an empty image for painting on. Instead of loading your images, you must draw them on the QCanvas.

QCanvas Properties
Field Type R/W Default Support
Align INTEGER RW alNone W
Align determines how the control aligns within its parent control.
ClientHeight INTEGER RW W
ClientWidth INTEGER RW W
Color INTEGER RW WXG
CopyMode INTEGER RW cmBlackness W
Cursor INTEGER RW crDefault W
Enabled INTEGER RW True WXG
Font QFONT W W
Height INTEGER RW WXG
Hint STRING RW W
Left INTEGER RW 0 WXG
Parent QFORM/QPANEL/QTABCONTROL W WXG
Pixel 2D ARRAY of INTEGER RW WXG
PopupMenu QPOPUPMENU W W
ShowHint INTEGER RW False W
Tag INTEGER RW WXG
Top INTEGER RW 0 WXG
Width INTEGER RW WXG
Visible INTEGER RW True WXG


QCanvas Methods
Method Type Description Params Support
Circle SUB (x1%, y1%, x2%, y2%, c%, fill%) Draw & Fill Circle 6 WXG
CopyRect SUB (D, Image, S) D and S are QRECTs, Image can be a QImage, QCanvas, or QBitmap 3 W
Example (copies QIMAGE to canvas at 10,10):
DIM Destination AS QRECT
DIM Source AS QRECT
DIM Image AS QIMAGE
Image.BMP = "whatever.bmp"

SUB CanvasPaint (Sender AS QCANVAS)
WITH Destination
.Top = 10
.Left = 10
.Right = .Left+Image.Width
.Bottom = .Top+Image.Height
END WITH
WITH Source
.Top = 0
.Left = 0
.Right = Image.Width
.Bottom = Image.Height
END WITH
Sender.CopyRect(Destination, Image, Source)
END SUB

DIM Canvas AS QCANVAS
Canvas.OnPaint = CanvasPaint
Draw SUB (x%, y%, BMP) Draw Bitmap on Canvas 3 WG
Details:
BMP can be any BMP property from QBitmap, QImage, QImageList, etc. any component with a BMP property is fine.
Examples:
DIM Image1 AS QIMAGE
Image1.BMP = "whatever.bmp"
DIM Image2 AS QBITMAP
Image2.BMP = "whatever.bmp"

SUB CanvasPaint (Sender AS QCANVAS)
Sender.Draw(0, 0, Image1.BMP)
Sender.Draw(50, 50, Image2.BMP)
END SUB

DIM Canvas AS QCANVAS
Canvas.OnPaint = CanvasPaint
FillRect SUB (x1%, y1%, x2%, y2%, c%) Draws & Fills a rectangle 5 WXG
Line SUB (x1%, y1%, x2%, y2%, c%) Draws a line 5 WXG
Paint SUB (x%, y%, c%, borderc%) Fill Region 4 WXG
Pset SUB (x%, y%, c%) Pixel plot 3 WXG
Rectangle SUB (x1%, y1%, x2%, y2%, c%) Draws a rectangle 5 WXG
Repaint SUB Force repainting 0 W
Rotate SUB (xOrigin%, yOrigin%, Angle%) Rotates entire canvas at specified origin 3 W
RoundRect SUB (x1%, y1%, x2%, y2%, x3%, y3%, c%) Draws & Fills a rounded rectangle 7 W
StretchDraw SUB (Rect AS QRECT, BMP) Draw image and stretch to fit inside Rect 2 W
TextHeight FUNCTION (Text$) AS WORD Returns the height, in pixels, of Text$ string 1 W
TextWidth FUNCTION (Text$) AS WORD Returns the width, in pixels, of Text$ string 1 W
TextRect SUB (Rect AS QRECT, x%, y%, S$, fc%, bc%) Write text, and clip within region Rect 6 W
TextOut SUB (x%, y%, S$, fc%, bc%) Writes text to image 5 WXG

QCanvas Events
Event Type Occurs when... Params Support
OnClick VOID User clicked on canvas 0 WXG
OnDblClick VOID User double clicked on canvas 0 W
OnMouseDown SUB (Button%, X%, Y%, Shift%) Mouse button held down 4 WXG
OnMouseMove SUB (X%, Y%, Shift%) Mouse moves 3 WXG
OnMouseUp SUB (Button%, X%, Y%, Shift%) Mouse button is released 4 WXG
OnPaint VOID Receives WM_PAINT message 0 WXG


QCanvas Examples 
'  Pixel by pixel credit scroller for Rapid-Q by William Yu

DIM Canvas AS QCanvas
DIM Form AS QForm
DIM Timer1 AS QTimer
DIM Font AS QFont
DIM Y AS INTEGER
    Y = -20

SUB Resize
  Canvas.Height = Form.ClientHeight
  Canvas.Width = Form.ClientWidth
END SUB

SUB Paint
  Canvas.Textout (65,Y-30,"Beware the power of Rapid-Q!", &H00FF00, 0)
  Canvas.Textout (30,Y,"Credit Scroller written in Rapid-Q by William Yu", &HFFFFFF, 0)
END SUB

SUB TimerOver
  Timer1.Interval = 1  '' Can't go any lower!
  Y = Y + 1            '' Pixel by pixel!
  Paint
END SUB

Form.Width = 400
Form.Height = 200
Form.Center
Form.Color = 0

Font.Name = "Arial"
Font.Size = 12
Font.Color = &H00FF00
Canvas.Parent = Form
Canvas.Font = Font
Canvas.Color = 0
Canvas.OnPaint = Paint

Timer1.Interval = 1
Timer1.OnTimer = TimerOver

Form.Onresize = Resize
Form.ShowModal
Prev ComponentContentsNext Component