Re: DrawImageUnscaled not working - C# Discussion Boards

Re: DrawImageUnscaled not working

25-Feb-09 7:43

I'm designing a small vector graphics app. Right now I'm writing code for painting a shape as it's being moved. For move operations, the shape is painted to a bitmap buffer so refreshes can be more effecient. Everything is working fine except when the drawing surface is scaled (zoomed).

The scaling factor is applied to the Graphics object when a paint message is called. That scaling factor is also used to generate a scaled "move bitmap" for the shape. For example, if the physical size of the shape is: 100 x 100 and the scaling factor is 50% then the move bitmap will be 50 x 50. The bitmap is then drawn as unscaled.

The problem is that the DrawImageUnscaled() method is not working! I get the same scaled results as if I were calling the DrawImage() method. This is rendering the scaled "move bitmap" to an additionaly scaled size!

Has anyone experienced this before?

//Code sample

private void initMoveBitmap()
{
//if the scaling factor is .50 the GetScaledBounds will produce a 50x50 on a 100x100 size
Rectangle r = shape.GetScaledBounds();
bmpMove = new Bitmap(r.Width, r.Height);

System.Drawing.Graphics gr = System.Drawing.Graphics.FromImage(bmpMove);
gr.TranslateTransform(-r.X, -r.Y);
gr.ScaleTransform(scale, scale);
paint_move_bitmap(gr);
gr.Dispose();
gr = null;
}

public void PaintShape(Graphics g)
{
//scenario: the graphics object has a scaling factor of .50

if (bmpMove != null)
//produces no difference from the DrawImage() method
graphics.DrawImageUnscaled(bmpMove, pntBmpPos);
else
//paint the shape.. (code excluded)
}

My code this week has no errors. But it's Monday morning and I haven't got out of bed.

Luc Pattyn25-Feb-09 9:24

Luc Pattyn

25-Feb-09 9:24

Hi Richard,

let me say for starters I never used DrawImageUnscaled; however this is how I understand the Graphics class: there are two different reasons why DrawImage may scale an image:

1. the transformation stuff (properties and methods relating to Matrix and ScaleTransform);
2. the parameters specifying a destination rectangle, and either the entire source image or a specified rectangular part of it.

AFAIK DrawImageUnscaled removes the second reason by ignoring the width and height if you specify one,
but I don't expect it to ignore the first reason. I expect the ScaleTransform/Matrix to rescale everything, like a Xerox copier could, supporting things such as putting several pages of a document on a single sheet of print.

Hope this helps.

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modified on Sunday, June 12, 2011 8:39 AM

Form Key Down Even not activated?

Muammar©25-Feb-09 7:36

Muammar©

25-Feb-09 7:36

Hi everyone,
Any idea why might the key_down_even of a form may be inactive?? I'm running a simple form with a tabControl and even when I set the focus back to the form, it doesnt capture the key strokes while it works fine on an empty form!

Please help

All generalizations are wrong, including this one!
(\ /)
(O.o)
(><)

Re: Form Key Down Even not activated?

Richard Blythe25-Feb-09 7:44

Re: Form Key Down Even not activated?

25-Feb-09 7:44

Does the focus remain on the tab control?

My code this week has no errors. But it's Monday morning and I haven't got out of bed.

Muammar©25-Feb-09 7:48

Muammar©

25-Feb-09 7:48

Ok, I found it, I just had to set the this.KeyPreview to true!
Thanks guys!

All generalizations are wrong, including this one!
(\ /)
(O.o)
(><)

is there a better way to do [modified]

netJP12L25-Feb-09 7:18

netJP12L

25-Feb-09 7:18

Hi guys, I have many controls inside a listbox and am displaying the listbox on the left side of the form. If a control is selected a corrospoding control is displayed on the right side of the form.

Simple.

The selected control from the listbox (right sided) control can be zoom like (75%,50%,25%). So for instance, if I zoom, 75% all the elements
inside the control are zoom as well (reflecting the 75%).

Hope it makes sense. Alright...

But how can I display controls inside the listbox not to be 75%. Because the right side pane hold a refece of the selected control from the listbox. so if right side Control is zoom to 75% all its elements reflect to 75% like(Size/Location). All controls inside the listbox should be zoom to 100%

                Form.cs
|---------------------------------------------------
|                                                  |
|             SplitContainer                       |
|  |---------------------------------------------  |
|  |           |        zoom(75%,50%,25%)       |  |
|  |           |     |-----------------------   |  |
|  | control1  |     |                      |   |  |
|  |           |     |                      |   |  |
|  |-----------|     |                      |   |  |
|  |           |     |  Control 2           |   |  |
|  | control2  |     |  is being displayed  |   |  |
|  |           |     |  and it is selected  |   |  |
|  |-----------|     |                      |   |  |
|  |           |     |                      |   |  |
|  | control3  |     |                      |   |  |
|  |           |     -----------------------    |  |
|  ---------------------------------------------   |
|                                                  |
|--------------------------------------------------

The way I solved this issue is that during the OnDrawItem event of the listbox I am making a copy of an individual
elements, resetting their Size and Location to the
zoom factor of 100% and then readding to new control.

I would apprecaite for your kind suggestions
Thanks

modified on Wednesday, February 25, 2009 1:57 PM

Richard Blythe25-Feb-09 7:50

25-Feb-09 7:50

If you're applying the scaling to the form where all controls reside then it is obviously going to scale everything, including your listbox. A better option would be to make your controls on the "right-side" to be UserControls. Scaling can be applied to it alone without affecting any other control.

Hope this helps,
Richard

My code this week has no errors. But it's Monday morning and I haven't got out of bed.

Dan Neely25-Feb-09 8:07

Dan Neely

25-Feb-09 8:07

Would splitting your zoom/nonzoomed controls into separate panels and only applying the zoom to the former's panel work?

Today's lesson is brought to you by the word "niggardly". Remember kids, don't attribute to racism what can be explained by Scandinavian language roots.
-- Robert Royall

Richard Blythe25-Feb-09 8:16

25-Feb-09 8:16

Good idea. I personally like user controls because it allows you create your layout in design mode. Either method should work.

There cannot be a crisis today; my schedule is already full.

Re: is there a better way to do [modified]

Dan Neely25-Feb-09 8:54

Dan Neely

25-Feb-09 8:54

How is creating a user control in design mode different from dragging controls onto a panel is design mode if you're only going to use the assemblage once? Obviously the control is better for something being used in many places.

Today's lesson is brought to you by the word "niggardly". Remember kids, don't attribute to racism what can be explained by Scandinavian language roots.
-- Robert Royall

netJP12L25-Feb-09 9:02

netJP12L

25-Feb-09 9:02

Thanks guys for replying back. I have made some changes to my orginal post.

Basically, you guys are suggesting me to apply the zoom to the right side control only.

The problem is that the right side Control that is being displayed is a referenced object and if a change is made to it reflects back to the corrosponding control that is shown in the listbox.

I am carring on my previous example, let's say from the listbox control2 is selected has an element (a button with Size 100,100 and Location 0,200) and that is also shown. If zoom is applied to 75% the Size and Location are now reflected to 75%. So the control2 elements on the right side, its size becomes (75,75) and location (0,75).
Since we orignally had a reference to the Control2 object if a change is made through the right side it also reflect back in the listbox.

modified on Wednesday, February 25, 2009 2:11 PM

Find Control on webform

Terick25-Feb-09 6:12

25-Feb-09 6:12

Hi,

I have a button on my webform that I need to access from my user control code behind, not the page on which the button resides, but I'm not sure how I find it.

I've thought it would be something like this, but this doesnt work:

Button button=(Button)FindControl("btn");

Thanks!

J4amieC25-Feb-09 6:38

J4amieC

25-Feb-09 6:38

Have you tried Page.FindControl("..")?

Terick25-Feb-09 7:03

25-Feb-09 7:03

Yes have tried that:

Button button=(Button)Page.FindControl("btn");

The Page will return the correct page, but nothing gets assigned to button, so I am getting nullReferenceException error.

Terick25-Feb-09 7:28

25-Feb-09 7:28

When I drill down into the error, into the Page property, the Page directs itself correctly and the button is listed under the [ASP.Page_aspx] base but there is no FindControl option listed. Any ideas as to why this is?

Rutvik Dave25-Feb-09 9:43

Rutvik Dave

25-Feb-09 9:43

I hope that Button is not in the ContentPlaceHolder and you are not using MasterPages.

Try

Page.Parent.FindControl()

If that button is inside the ContentPlaceHolder then stack trace and find the actual value for that button. something like xxxxxctl001_btn.

then first find the content place holder (or any other container)
using

container c = Page.FindControl('container') and then c.FindControl('btn')

PS: container means any container i.e. Panel / ContentPlaceHolder etc...

Terick25-Feb-09 12:04