Gambas/Graphics

Back to Gambas If you want to produce some graphics in gambas you should get used to the drawingarea control. Draw a Line This little program will draw a line. You have to start a new graphics project. You take a form as your start form. You need a drawingarea and a commandbutton on the form to get it going. PUBLIC SUB Button1_Click() Draw.Begin(DrawingArea1) Draw.Line(1, 130, 500, 400) Draw.End END When you want to draw some more lines, then try this example: PUBLIC SUB Form_Open() DIM B AS Integer Draw.Begin(DrawingArea1) FOR B = 1 TO 200 STEP 10 Draw.Line(1, B, 500, B) NEXT Draw.End END Some other lines are drawn here: PUBLIC SUB Button1_Click() DIM B AS Integer Draw.Begin(DrawingArea1) ' Draws a line horizontally across the centre of the form Draw.Line (0, ME.Height / 2, ME.Width, ME.Height / 2) ' Draws a line vertically down the centre of the form Draw.Line (ME.Width / 2, 0,ME.Width / 2, ME.Height) ' Draws a line from the top left, to the bottom right Draw.Line (0, 0,ME.Width, ME.Height) ' Draws a line from the top right, to the bottom left Draw.Line (ME.Width, 0,0, ME.Height) Draw.End END When you want to manipulate the width of your line , then try this example: PUBLIC SUB Form_Open() DIM B AS Integer Draw.Begin(DrawingArea1) Draw.Line(10,100, 20, 100) FOR B = 1 TO 100 STEP 10 Draw.LineWidth=B Draw.Line(10+B,100, 20+B, 100) NEXT Draw.End END If you want to change the color of your line to white, then try this example: Draw.Begin(DrawingArea1) Draw.ForeColor = &HFFFFFF Draw.Line(1, 130, 500, 400) Draw.End The next small example will draw a box and fill it with white color. PUBLIC SUB Button1_Click() Draw.Begin(DrawingArea1) Draw.FillColor = &HFFFFFF draw.FillStyle = 1 'draw.ForeColor = &HFFFFFF the outline will be white also Draw.Rect (100, 100,200,200) Draw.End END The Spiral Program This program shows you a nice spiral. There is no scale command in Gambas (at least, not yet). Therefore the x and y coordinates are transformed in the program. The coordinate system ranges from xmin = - 2 to xmax = 2 and ymin = - 2 to ymax = 2. You need a Drawingarea and a Commandbutton to get the example going. How does this look ? See The code: PUBLIC SUB Button1_Click() DIM dymax AS Integer DIM dymin AS Integer DIM ymax AS Integer DIM ymin AS Integer DIM y AS Float DIM dy AS Float DIM dyi AS Integer DIM dxmax AS Integer DIM dxmin AS Integer DIM xmax AS Integer DIM xmin AS Integer DIM x AS Float DIM dx AS Float DIM dxi AS Integer DIM k AS Float DIM a AS Float DIM w AS Float dymax = DrawingArea1.Height dymin = 0 ymax = 2 ymin = -2 dxmax = DrawingArea1.Width dxmin = 0 xmax = 2 xmin = -2 'x-axis is drawn FOR x = xmin TO xmax STEP 0.005 y = 0 dy = CFloat(y - ymin) / (ymax - ymin ) * (dymax - dymin) + dymin dx = CFloat(x - xmin) / (xmax - xmin ) * (dxmax - dxmin) + dxmin dyi = Fix(dy) dxi = Fix(dx) Draw.Begin(DrawingArea1) Draw.Point(dxi,DrawingArea1.Height- dyi) Draw.End NEXT 'y - Axis is drawn FOR y = ymin TO ymax STEP 0.005 x = 0 dy = CFloat(y - ymin) / (ymax - ymin ) * (dymax - dymin) + dymin dx = CFloat(x - xmin) / (xmax - xmin ) * (dxmax - dxmin) + dxmin dyi = Fix(dy) dxi = Fix(dx) Draw.Begin(DrawingArea1) Draw.Point(dxi,DrawingArea1.Height- dyi) Draw.End NEXT 'Here the spiral starts FOR k = -100 TO 150 STEP 0.5 a = 0.97 'Distance from 0,0 to the point w = 0.15 'Angle under whiche the point is seen from the origin a = a ^k w = w * k x = a * Cos(w) 'x coordinate of each point y = a * Sin(w) 'y coordinate of each point dy = CFloat(y - ymin) / (ymax - ymin ) * (dymax - dymin) + dymin dx = CFloat(x - xmin) / (xmax - xmin ) * (dxmax - dxmin) + dxmin dyi = Fix(dy) dxi = Fix(dx) Draw.Begin(DrawingArea1) Draw.Point(dxi,DrawingArea1.Height- dyi) Draw.End NEXT END