| /***************************************************************************/ |
| /* */ |
| /* ftbbox.c */ |
| /* */ |
| /* FreeType bbox computation (body). */ |
| /* */ |
| /* Copyright 1996-1999 by */ |
| /* David Turner, Robert Wilhelm, and Werner Lemberg. */ |
| /* */ |
| /* This file is part of the FreeType project, and may only be used */ |
| /* modified and distributed under the terms of the FreeType project */ |
| /* license, LICENSE.TXT. By continuing to use, modify, or distribute */ |
| /* this file you indicate that you have read the license and */ |
| /* understand and accept it fully. */ |
| /* */ |
| /***************************************************************************/ |
| |
| |
| /*************************************************************************/ |
| /* */ |
| /* This component has a _single_ role: to compute exact outline bounding */ |
| /* boxes. */ |
| /* */ |
| /* It is separated from the rest of the engine for various technical */ |
| /* reasons. It may well be integrated in `ftoutln' later. */ |
| /* */ |
| /*************************************************************************/ |
| |
| |
| #include <ftbbox.h> |
| #include <ftimage.h> |
| #include <ftobjs.h> |
| |
| typedef struct TBBox_Rec_ |
| { |
| FT_Vector last; |
| FT_BBox bbox; |
| |
| } TBBox_Rec; |
| |
| |
| /*************************************************************************/ |
| /* */ |
| /* <Function> */ |
| /* BBox_Move_To */ |
| /* */ |
| /* <Description> */ |
| /* This function is used as a `move_to' and `line_to' emitter during */ |
| /* FT_Raster_Decompose(). It simply records the destination point in */ |
| /* user->last. */ |
| /* */ |
| /* <Input> */ |
| /* to :: The destination vector. */ |
| /* user :: The current walk context. */ |
| /* */ |
| /* <Return> */ |
| /* Error code. 0 means success. */ |
| /* */ |
| static |
| int BBox_Move_To( FT_Vector* to, |
| TBBox_Rec* user ) |
| { |
| user->last = *to; |
| |
| return 0; |
| } |
| |
| |
| #define CHECK_X( p, bbox ) \ |
| ( p->x < bbox.xMin || p->x > bbox.xMax ) |
| |
| #define CHECK_Y( p, bbox ) \ |
| ( p->y < bbox.yMin || p->y > bbox.yMax ) |
| |
| |
| /*************************************************************************/ |
| /* */ |
| /* <Function> */ |
| /* BBox_Conic_Check */ |
| /* */ |
| /* <Description> */ |
| /* Finds the extrema of a 1-dimensional conic Bezier curve and update */ |
| /* a bounding range. This version uses direct computation, as it */ |
| /* doesn't need square roots. */ |
| /* */ |
| /* <Input> */ |
| /* y1 :: The start coordinate. */ |
| /* y2 :: The coordinate of the control point. */ |
| /* y3 :: The end coordinate. */ |
| /* */ |
| /* <Output> */ |
| /* min :: The address of the current minimum. */ |
| /* max :: The address of the current maximum. */ |
| /* */ |
| static |
| void BBox_Conic_Check( FT_Pos y1, |
| FT_Pos y2, |
| FT_Pos y3, |
| FT_Pos* min, |
| FT_Pos* max ) |
| { |
| if( y1 == y3 ) |
| { |
| if ( y2 == y1 ) /* Flat arc */ |
| { |
| y3 = y1; |
| goto Suite; |
| } |
| } |
| else if ( y1 < y3 ) |
| { |
| if ( y2 >= y1 && y2 <= y3 ) /* Ascending arc */ |
| goto Suite; |
| } |
| else |
| { |
| if ( y2 >= y3 && y2 <= y1 ) /* Descending arc */ |
| { |
| y2 = y1; |
| y1 = y3; |
| y3 = y2; |
| goto Suite; |
| } |
| } |
| |
| y1 = y3 = FT_MulDiv( y2 - y1, y2 - y1, y1 - 2*y2 + y3 ); |
| |
| Suite: |
| if ( y1 < *min ) *min = y1; |
| if ( y3 > *max ) *max = y3; |
| } |
| |
| |
| /*************************************************************************/ |
| /* */ |
| /* <Function> */ |
| /* BBox_Conic_To */ |
| /* */ |
| /* <Description> */ |
| /* This function is used as a `conic_to' emitter during */ |
| /* FT_Raster_Decompose(). It checks a conic Bezier curve with the */ |
| /* current bounding box, and computes its extrema if necessary to */ |
| /* update it. */ |
| /* */ |
| /* <Input> */ |
| /* control :: A control point. */ |
| /* to :: The destination vector. */ |
| /* */ |
| /* <InOut> */ |
| /* user :: The current walk context. */ |
| /* */ |
| /* <Return> */ |
| /* Error code. 0 means success. */ |
| /* */ |
| /* <Note> */ |
| /* In the case of a non-monotonous arc, we compute directly the */ |
| /* extremum coordinates, as it is sufficiently fast. */ |
| /* */ |
| static |
| int BBox_Conic_To( FT_Vector* control, |
| FT_Vector* to, |
| TBBox_Rec* user ) |
| { |
| if ( CHECK_X( control, user->bbox ) || |
| CHECK_X( to, user->bbox ) ) |
| |
| BBox_Conic_Check( user->last.x, |
| control->x, |
| to->x, |
| &user->bbox.xMin, |
| &user->bbox.xMax ); |
| |
| if ( CHECK_Y( control, user->bbox ) || |
| CHECK_Y( to, user->bbox ) ) |
| |
| BBox_Conic_Check( user->last.y, |
| control->y, |
| to->y, |
| &user->bbox.yMin, |
| &user->bbox.yMax ); |
| |
| return 0; |
| } |
| |
| |
| /*************************************************************************/ |
| /* */ |
| /* <Function> */ |
| /* BBox_Cubic_Check */ |
| /* */ |
| /* <Description> */ |
| /* Finds the extrema of a 1-dimensional cubic Bezier curve and */ |
| /* updates a bounding range. This version uses splitting because we */ |
| /* don't want to use square roots and extra accuracies. */ |
| /* */ |
| /* <Input> */ |
| /* p1 :: The start coordinate. */ |
| /* p2 :: The coordinate of the first control point. */ |
| /* p3 :: The coordinate of the second control point. */ |
| /* p4 :: The end coordinate. */ |
| /* */ |
| /* <InOut> */ |
| /* min :: The address of the current minimum. */ |
| /* max :: The address of the current maximum. */ |
| /* */ |
| static |
| void BBox_Cubic_Check( FT_Pos p1, |
| FT_Pos p2, |
| FT_Pos p3, |
| FT_Pos p4, |
| FT_Pos* min, |
| FT_Pos* max ) |
| { |
| FT_Pos stack[33], *arc; |
| |
| |
| arc = stack; |
| |
| arc[0] = p1; |
| arc[1] = p2; |
| arc[2] = p3; |
| arc[3] = p4; |
| |
| do |
| { |
| FT_Pos y1 = arc[0]; |
| FT_Pos y2 = arc[1]; |
| FT_Pos y3 = arc[2]; |
| FT_Pos y4 = arc[3]; |
| |
| |
| if ( y1 == y4 ) |
| { |
| if ( y1 == y2 && y1 == y3 ) /* Flat */ |
| { |
| y4 = y1; |
| goto Test; |
| } |
| } |
| else if ( y1 < y4 ) |
| { |
| if ( y2 >= y1 && y2 <= y4 && y3 >= y1 && y3 <= y4 ) /* Ascending */ |
| goto Test; |
| } |
| else |
| { |
| if ( y2 >= y4 && y2 <= y1 && y3 >= y4 && y3 <= y1 ) /* Descending */ |
| { |
| y2 = y1; |
| y1 = y4; |
| y4 = y2; |
| goto Test; |
| } |
| } |
| |
| /* Unknown direction, split the arc in two */ |
| arc[6] = y4; |
| arc[1] = y1 = ( y1 + y2 ) / 2; |
| arc[5] = y4 = ( y4 + y3 ) / 2; |
| y2 = ( y2 + y3 ) / 2; |
| arc[2] = y1 = ( y1 + y2 ) / 2; |
| arc[4] = y4 = ( y4 + y2 ) / 2; |
| arc[3] = ( y1 + y4 ) / 2; |
| |
| arc += 3; |
| goto Suite; |
| |
| Test: |
| if ( y1 < *min ) *min = y1; |
| if ( y4 > *max ) *max = y4; |
| arc -= 3; |
| |
| Suite: |
| ; |
| } while (arc >= stack); |
| } |
| |
| |
| /*************************************************************************/ |
| /* */ |
| /* <Function> */ |
| /* BBox_Cubic_To */ |
| /* */ |
| /* <Description> */ |
| /* This function is used as a `cubic_to' emitter during */ |
| /* FT_Raster_Decompose(). It checks a cubic Bezier curve with the */ |
| /* current bounding box, and computes its extrema if necessary to */ |
| /* update it. */ |
| /* */ |
| /* <Input> */ |
| /* control1 :: The first control point. */ |
| /* control2 :: The second control point. */ |
| /* to :: The destination vector. */ |
| /* */ |
| /* <InOut> */ |
| /* user :: The current walk context. */ |
| /* */ |
| /* <Return> */ |
| /* Error code. 0 means success. */ |
| /* */ |
| /* <Note> */ |
| /* In the case of a non-monotonous arc, we don't compute directly */ |
| /* extremum coordinates, we subdivise instead. */ |
| /* */ |
| static |
| int BBox_Cubic_To( FT_Vector* control1, |
| FT_Vector* control2, |
| FT_Vector* to, |
| TBBox_Rec* user ) |
| { |
| if ( CHECK_X( control1, user->bbox ) || |
| CHECK_X( control2, user->bbox ) || |
| CHECK_X( to, user->bbox ) ) |
| |
| BBox_Cubic_Check( user->last.x, |
| control1->x, |
| control2->x, |
| to->x, |
| &user->bbox.xMin, |
| &user->bbox.xMax ); |
| |
| if ( CHECK_Y( control1, user->bbox ) || |
| CHECK_Y( control2, user->bbox ) || |
| CHECK_Y( to, user->bbox ) ) |
| |
| BBox_Cubic_Check( user->last.y, |
| control1->y, |
| control2->y, |
| to->y, |
| &user->bbox.yMin, |
| &user->bbox.yMax ); |
| |
| return 0; |
| } |
| |
| |
| /*************************************************************************/ |
| /* */ |
| /* <Function> */ |
| /* FT_Raster_GetBBox */ |
| /* */ |
| /* <Description> */ |
| /* Computes the exact bounding box of an outline. This is slower */ |
| /* than computing the control box. However, it uses an advanced */ |
| /* algorithm which returns _very_ quickly when the two boxes */ |
| /* coincide. Otherwise, the outline Bezier arcs are walked over to */ |
| /* extract their extrema. */ |
| /* */ |
| /* <Input> */ |
| /* outline :: A pointer to the source outline. */ |
| /* */ |
| /* <Output> */ |
| /* bbox :: The outline's exact bounding box. */ |
| /* */ |
| /* <Return> */ |
| /* Error code. 0 means success. */ |
| /* */ |
| EXPORT_FUNC |
| FT_Error FT_Raster_GetBBox( FT_Outline* outline, |
| FT_BBox* abbox ) |
| { |
| FT_BBox cbox; |
| FT_BBox bbox; |
| FT_Vector* vec; |
| FT_UShort n; |
| |
| |
| /* if outline is empty, return (0,0,0,0) */ |
| if ( !outline ) |
| return FT_Err_Invalid_Outline; |
| |
| if ( outline->n_points == 0 || outline->n_contours <= 0 ) |
| { |
| abbox->xMin = abbox->xMax = 0; |
| abbox->yMin = abbox->yMax = 0; |
| return 0; |
| } |
| |
| /* We compute the control box, as well as the bounding box */ |
| /* of all `on' points in the outline. Then, if the two boxes */ |
| /* coincide, we exit immediately. */ |
| |
| vec = outline->points; |
| bbox.xMin = bbox.xMax = cbox.xMin = cbox.xMax = vec->x; |
| bbox.yMin = bbox.yMin = cbox.yMin = cbox.yMax = vec->y; |
| |
| for ( n = 1; n < outline->n_points; n++ ) |
| { |
| FT_Pos x = vec->x; |
| FT_Pos y = vec->y; |
| |
| |
| /* update control box */ |
| if ( x < cbox.xMin ) cbox.xMin = x; |
| if ( x > cbox.xMax ) cbox.xMax = x; |
| |
| if ( y < cbox.yMin ) cbox.yMin = y; |
| if ( y > cbox.yMax ) cbox.yMax = y; |
| |
| if ( FT_CURVE_TAG( outline->flags[n] ) == FT_Curve_Tag_On ) |
| { |
| /* update bbox for `on' points only */ |
| if ( x < bbox.xMin ) bbox.xMin = x; |
| if ( x > bbox.xMax ) bbox.xMax = x; |
| |
| if ( y < bbox.yMin ) bbox.yMin = y; |
| if ( y > bbox.yMax ) bbox.yMax = y; |
| } |
| |
| vec++; |
| } |
| |
| /* test two boxes for equality */ |
| if ( cbox.xMin < bbox.xMin || cbox.xMax > bbox.xMax || |
| cbox.yMin < bbox.yMin || cbox.yMax > bbox.yMax ) |
| { |
| /* the two boxes are different, now walk over the outline to */ |
| /* get the Bezier arc extrema. */ |
| |
| static FT_Outline_Funcs interface = |
| { |
| (FT_Outline_MoveTo_Func) BBox_Move_To, |
| (FT_Outline_LineTo_Func) BBox_Move_To, |
| (FT_Outline_ConicTo_Func) BBox_Conic_To, |
| (FT_Outline_CubicTo_Func) BBox_Cubic_To |
| }; |
| |
| FT_Error error; |
| TBBox_Rec user; |
| |
| |
| user.bbox = bbox; |
| |
| error = FT_Decompose_Outline( outline, &interface, &user ); |
| if ( error ) |
| return error; |
| |
| *abbox = user.bbox; |
| } |
| else |
| *abbox = bbox; |
| |
| return FT_Err_Ok; |
| } |
| |
| |
| /* END */ |
