Rotate rerctangle in Bitmap

[raju_shiva]

CPallini wrote:

I see no rectangle here

After getting all the values Here i am drawing the rectangle

MoveToEx(pCellInfo->hDC,center.x-x1,center.y-y2,NULL);
LineTo(pCellInfo->hDC,center.x-x1,center.y+y1);
LineTo(pCellInfo->hDC,center.x+x2,center.y+y1);
LineTo(pCellInfo->hDC,center.x+x2,center.y-y2);
LineTo(pCellInfo->hDC,center.x-x1,center.y-y2);

Thanks Raj

[CPallini]

OK (sorry if I didn't get you). Now, what is the problem with your code (expected behaviour vs observed one)?. :)

If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler. -- Alfonso the Wise, 13th Century King of Castile.
This is going on my arrogant assumptions. You may have a superb reason why I'm completely wrong. -- Iain Clarke
[My articles]

[raju_shiva]

Now i want to rotate it for the given degree.How can i do it. I am bit confused please help me Thanks Raj

[CPallini]

You are defining the rectangle via offsets from center, that is

P0={-x1,-y2}, P1{-x1, y1}, P2={x2,y1}, P3={x2,-y2}

hence, if you wan't rotate with angle phi around the center, than you should compute:

Pr = { x * cos(phi) + y * sin(phi), -x * sin(phi) + y * cos(phi)}

i.e.:

P0R= { -x1 * cos(phi) -y2*sin(phi), x1 * sin(phi) - y2 * cos(phi)}
P1R =...
P2R =...
P3R =...

and then connect the center+PiR points the way you did before. :)

If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler. -- Alfonso the Wise, 13th Century King of Castile.
This is going on my arrogant assumptions. You may have a superb reason why I'm completely wrong. -- Iain Clarke
[My articles]

[raju_shiva]

CPallini wrote:

P0R= { -x1 * cos(phi) -y2*sin(phi), x1 * sin(phi) - y2 * cos(phi)}

I am confused with it??? Now suppose my values are:

x1 = 330,x2 = 330,y1=330,y2=330
Origin(center.x,cebter.y) = Origin(525,454);

I have to do the get the new x1,x2,y1,y2 before calling MoveToEx and LineTo Am i right?? i.e

Pr = { x * cos(phi) + y * sin(phi), -x * sin(phi) + y * cos(phi)}

for each x1,x2,y1,y2. Then call the function

MoveToEx(pCellInfo->hDC,center.x-x1,center.y-y2,NULL); // where x1 = Pr1,x2=Pr2....y2 = Pr4
LineTo(pCellInfo->hDC,center.x-x1,center.y+y1);
LineTo(pCellInfo->hDC,center.x+x2,center.y+y1);
LineTo(pCellInfo->hDC,center.x+x2,center.y-y2);
LineTo(pCellInfo->hDC,center.x-x1,center.y-y2);

Thanks Raj

[CPallini]

Something like this

// rotate around center
double phi = atan(1.0) * 2/3; // 30 degrees
int x[4];
int y[4];
x[0] = -x1 * cos(phi) - y2 * sin(phi);
y[0] = x1 * sin(phi) - y2 * cos(phi);

x[1] = -x1 * cos(phi) + y1 * sin(phi);
y[1] = x1 * sin(phi) + y1 * cos(phi);

x[2] = x2 * cos(phi) + y1 * sin(phi);
y[2] = -x2 * sin(phi) + y1 * cos(phi);

x[3] = x2 * cos(phi) - y2 * sin(phi);
y[3] = -x2 * sin(phi) - y2 * cos(phi);

for (int i=0; i<4; i++)
{
x[i] += center.x;
y[i] += center.y;
}

MoveToEx(pCellInfo->hDC,x[3],y[3],NULL);
for (int i=0; i<4; i++)
{
LineTo(pCellInfo->hDC, x[i],y[i]);
}

I suppose. :)

If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler. -- Alfonso the Wise, 13th Century King of Castile.
This is going on my arrogant assumptions. You may have a superb reason why I'm completely wrong. -- Iain Clarke
[My articles]

[Peter_in_2780]

When I said "look at the actual values", I didn't mean the expressions, I meant the actual values. In other words, either add some code to print out the values when you call the function or put a breakpoint on the call and inspect the values in your debugger. Then you should be able to figure out what is wrong and work back to where your problem is.

Software rusts. Simon Stephenson, ca 1994.

[raju_shiva]

Thanks a lot ,its working fine. Thanks Raj

[raju_shiva]

Thank u peter for your reply.Its working fine now Raj

[CPallini]

You are welcome. :)

If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler. -- Alfonso the Wise, 13th Century King of Castile.
This is going on my arrogant assumptions. You may have a superb reason why I'm completely wrong. -- Iain Clarke
[My articles]

[Rick York]

The code looks correct but I find it to be slightly offensive to me sensibilities. :) I'm just kidding. I usually make a function or method when I see a sequence of code repeated more than twice. Something like this is generic enough that I definitely would. Of course, it's not your job to put this is into a function. That is an exercise for the reader. ;)

[CPallini]

Rick York wrote:

he code looks correct but I find it to be slightly offensive to me sensibilities. Smile I'm just kidding. I usually make a function or method when I see a sequence of code repeated more than twice. Something like this is generic enough that I definitely would.

Nah, that's childish. You've to set up a linear algebra library, with vectors and rotation matrices, properly overloading the multiplication operator. Of course that's an exercise for you. ;P :laugh: On my defence, I wouldn't write such code repetitions in my own software (well, maybe I do in quick and dirty junk programs), the goal there was being as explicit as possible (the OP had doubts on the steps to take) :)

If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler. -- Alfonso the Wise, 13th Century King of Castile.
This is going on my arrogant assumptions. You may have a superb reason why I'm completely wrong. -- Iain Clarke
[My articles]