Write a short note on curve clipping and text clipping.

Write a short note on curve clipping and text clipping.

1 Answer

Curve clipping :-

  • Curve clipping procedures will involve non-linear equations, however, this requires more processing than for objects with linear boundaries.

  • The bounding rectangle for a circle or other curved object can be used first to test for overlap with a rectangular clip window.

  • If the bounding rectangle for the object is completely inside the window, we save the object.

  • If the bounding rectangle is determined to be completely outside the window, we discard the object.

  • This procedures can be applied when clipping a curved object against a general polygon clip region. On the first pass, we can clip the bounding rectangle of the object against the bounding rectangle of the clip region.

  • If the two regions overlap, we will need to solve the simultaneous line-curve equations to obtain the clipping intersection points.

Text clipping :-

  • Text clipping is a clipping in which we clip the whole character or only part of it and depends on the requirement of the application.

  • Following are the various text clipping methods :

    All-or-none string clipping method :

    • In this method, if all of the string is inside a clip window, we keep it. Otherwise, the string is discarded.

    • This method is implemented by considering a bounding rectangle around the text pattern.

    • The boundary positions of the rectangle are then compared to the window boundaries, and the string is rejected if there is any overlap.

    • This method produces the fastest text clipping.

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All-or-none character clipping method :

  • In this method, we keep the character of the strings which lies inside clip window, otherwise, discard it.

  • In this case, the boundary limits of individual characters are compared to the window.

  • Any character that either overlaps or is outside a window boundary is clipped.

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