Drawing spiral in java.........

[sumuka]

Hello ,

Im doing a java project in java 1.5 version and i need to draw the spiral . The problem is the user has to draw a box or rectangle of any size on an image and the central point of that box should be taken and a spiral should be drawn automatically starting from central point and also the box which they have drawn should be able to move and place it somewhere else in the picture. how to achieve this.

Kindly help me.
Thanks in anticipation.

[JosAH]

Hello ,

Im doing a java project in java 1.5 version and i need to draw the spiral . The problem is the user has to draw a box or rectangle of any size on an image and the central point of that box should be taken and a spiral should be drawn automatically starting from central point and also the box which they have drawn should be able to move and place it somewhere else in the picture. how to achieve this.

Kindly help me.
Thanks in anticipation.

The "should be able to move and place it somewhere else in the picture" is the
most complicated part of it all and you have to exactly define what user mouse
gesture does what:

1) The user clicks the mouse and keeps it clicked and moves the mouse; this
should (or could define a rectangular area).

2) when the user releases the mouse button the other corner of the rectangle is
defined and the spiral can be drawn.

3) The user clicks the mouse and keeps it clicked and moves the mouse. Now
what should be done? The compound gesture is identical to 1). Should a second
spiral be drawn or should the first spiral be moved if the mouse was clicked in
the bounds of the rectangle defined by prior steps 1) and 2)?

What should happen if the user repeats steps 1) and 2) *outside* the bounds of
the first rectangle?

Think this over before you start coding. The actual drawing of a spiral is the easy
part.

kind regards,

Jos

[sumuka]

The "should be able to move and place it somewhere else in the picture" is the
most complicated part of it all and you have to exactly define what user mouse
gesture does what:

1) The user clicks the mouse and keeps it clicked and moves the mouse; this
should (or could define a rectangular area).

2) when the user releases the mouse button the other corner of the rectangle is
defined and the spiral can be drawn.

3) The user clicks the mouse and keeps it clicked and moves the mouse. Now
what should be done? The compound gesture is identical to 1). Should a second
spiral be drawn or should the first spiral be moved if the mouse was clicked in
the bounds of the rectangle defined by prior steps 1) and 2)?

What should happen if the user repeats steps 1) and 2) *outside* the bounds of
the first rectangle?

Think this over before you start coding. The actual drawing of a spiral is the easy
part.

kind regards,

Jos

Thank you Jos for showing interest in my question.
Now As you said when the user clicks and drags on the image a rectangle with a dotted lines has to be drawn once the user releases the mouse a spiral has to be drawn automatically within the rectangle and the dotted lines should disappear and when the user clicks on rectangle and moves it to the desired location the only the spiral has to be moved without any change to the background image.
Help me out with this.

Thanks in anticipation,

[Ganon11]

Well, since I'm not sure how you'll take care of moving the Rectangle (as I'm not too good with Java graphics), I'll try and help with actually drawing the spiral.

You can draw this spiral by using polar coordinates. A common equation for a spiral is r = (constant)<theta>. You can modify the size of the spiral by changing the (constant) value to be larger or smaller, to match your preference. Then you need to know the (X, Y) point to represent this (r, <theta>) point in the polar coordinate system. Using the conversions x = r * cos(<theta>), y = r * sin(<theta>), and r = (constant) * <theta>, you can find the x and y point of any point in your spiral.

So now you have an X, Y position, relative to the origin. The origin should be the center of your rectangle, so you will have to use it's position, width, and height to calculate the center point, then translate your X, Y point the appropriate amount.

All this is to plot 1 point on your spiral. Now you just need to compute many values of <theta> to get a smooth spiral.

[sumuka]

Well, since I'm not sure how you'll take care of moving the Rectangle (as I'm not too good with Java graphics), I'll try and help with actually drawing the spiral.

You can draw this spiral by using polar coordinates. A common equation for a spiral is r = (constant)<theta>. You can modify the size of the spiral by changing the (constant) value to be larger or smaller, to match your preference. Then you need to know the (X, Y) point to represent this (r, <theta>) point in the polar coordinate system. Using the conversions x = r * cos(<theta>), y = r * sin(<theta>), and r = (constant) * <theta>, you can find the x and y point of any point in your spiral.

So now you have an X, Y position, relative to the origin. The origin should be the center of your rectangle, so you will have to use it's position, width, and height to calculate the center point, then translate your X, Y point the appropriate amount.

All this is to plot 1 point on your spiral. Now you just need to compute many values of <theta> to get a smooth spiral.

Thanks for replying
I will try this out and get back to you if i need any help. :)