## gimpitemtransform

gimpitemtransform — Functions to perform transformations on items.

## Synopsis

    gint32              gimp_item_transform_flip_simple     (gint32 item_ID,
                                                             GimpOrientationType flip_type,
                                                             gboolean auto_center,
                                                             gdouble axis);
    gint32              gimp_item_transform_flip            (gint32 item_ID,
                                                             gdouble x0,
                                                             gdouble y0,
                                                             gdouble x1,
                                                             gdouble y1);
    gint32              gimp_item_transform_perspective     (gint32 item_ID,
                                                             gdouble x0,
                                                             gdouble y0,
                                                             gdouble x1,
                                                             gdouble y1,
                                                             gdouble x2,
                                                             gdouble y2,
                                                             gdouble x3,
                                                             gdouble y3);
    gint32              gimp_item_transform_rotate_simple   (gint32 item_ID,
                                                             GimpRotationType rotate_type,
                                                             gboolean auto_center,
                                                             gdouble center_x,
                                                             gdouble center_y);
    gint32              gimp_item_transform_rotate          (gint32 item_ID,
                                                             gdouble angle,
                                                             gboolean auto_center,
                                                             gdouble center_x,
                                                             gdouble center_y);
    gint32              gimp_item_transform_scale           (gint32 item_ID,
                                                             gdouble x0,
                                                             gdouble y0,
                                                             gdouble x1,
                                                             gdouble y1);
    gint32              gimp_item_transform_shear           (gint32 item_ID,
                                                             GimpOrientationType shear_type,
                                                             gdouble magnitude);
    gint32              gimp_item_transform_2d              (gint32 item_ID,
                                                             gdouble source_x,
                                                             gdouble source_y,
                                                             gdouble scale_x,
                                                             gdouble scale_y,
                                                             gdouble angle,
                                                             gdouble dest_x,
                                                             gdouble dest_y);
    gint32              gimp_item_transform_matrix          (gint32 item_ID,
                                                             gdouble coeff_0_0,
                                                             gdouble coeff_0_1,
                                                             gdouble coeff_0_2,
                                                             gdouble coeff_1_0,
                                                             gdouble coeff_1_1,
                                                             gdouble coeff_1_2,
                                                             gdouble coeff_2_0,
                                                             gdouble coeff_2_1,
                                                             gdouble coeff_2_2);

## Description

Functions to perform transformations on items.

## Details

### gimp_item_transform_flip_simple ()

    gint32              gimp_item_transform_flip_simple     (gint32 item_ID,
                                                             GimpOrientationType flip_type,
                                                             gboolean auto_center,
                                                             gdouble axis);

Flip the specified item either vertically or horizontally.

This procedure flips the specified item. If a selection exists and the item is a drawable, the portion of the drawable which lies under the selection is cut from the drawable and made into a floating selection which is then flipped. If auto_center is set to TRUE, the flip is around the selection's center. Otherwise, the coordinate of the axis needs to be specified. The return value is the ID of the flipped item. If there was no selection or the item is not a drawable, this will be equal to the item ID supplied as input. Otherwise, this will be the newly created and flipped drawable. This procedure is affected by the following context setters: `gimp_context_set_transform_resize()`.

`item_ID` : | The affected item.
`flip_type` : | Type of flip.
`auto_center` : | Whether to automatically position the axis in the selection center.
`axis` : | coord. of flip axis.
Returns : | The flipped item.

Since GIMP 2.2

### gimp_item_transform_flip ()

    gint32              gimp_item_transform_flip            (gint32 item_ID,
                                                             gdouble x0,
                                                             gdouble y0,
                                                             gdouble x1,
                                                             gdouble y1);

Flip the specified item around a given line.

This procedure flips the specified item. If a selection exists and the item is a drawable , the portion of the drawable which lies under the selection is cut from the drawable and made into a floating selection which is then flipped. The axis to flip around is specified by specifying two points from that line. The return value is the ID of the flipped item. If there was no selection or the item is not a drawable, this will be equal to the item ID supplied as input. Otherwise, this will be the newly created and flipped drawable. This procedure is affected by the following context setters: `gimp_context_set_interpolation()`, `gimp_context_set_transform_direction()`, `gimp_context_set_transform_resize()`, `gimp_context_set_transform_recursion()`.

`item_ID` : | The affected item.
`x0` : | horz. coord. of one end of axis.
`y0` : | vert. coord. of one end of axis.
`x1` : | horz. coord. of other end of axis.
`y1` : | vert. coord. of other end of axis.
Returns : | The flipped item.

Since GIMP 2.8

### gimp_item_transform_perspective ()

    gint32              gimp_item_transform_perspective     (gint32 item_ID,
                                                             gdouble x0,
                                                             gdouble y0,
                                                             gdouble x1,
                                                             gdouble y1,
                                                             gdouble x2,
                                                             gdouble y2,
                                                             gdouble x3,
                                                             gdouble y3);

Perform a possibly non-affine transformation on the specified item.

This procedure performs a possibly non-affine transformation on the specified item by allowing the corners of the original bounding box to be arbitrarily remapped to any values. The specified item is remapped if no selection exists or it is not a drawable. However, if a selection exists and the item is a drawable, the portion of the drawable which lies under the selection is cut from the drawable and made into a floating selection which is then remapped as specified. The return value is the ID of the remapped item. If there was no selection or the item is not a drawable, this will be equal to the item ID supplied as input. Otherwise, this will be the newly created and remapped drawable. The 4 coordinates specify the new locations of each corner of the original bounding box. By specifying these values, any affine transformation (rotation, scaling, translation) can be affected. Additionally, these values can be specified such that the resulting transformed item will appear to have been projected via a perspective transform. This procedure is affected by the following context setters: `gimp_context_set_interpolation()`, `gimp_context_set_transform_direction()`, `gimp_context_set_transform_resize()`, `gimp_context_set_transform_recursion()`.

`item_ID` : | The affected item.
`x0` : | The new x coordinate of upper-left corner of original bounding box.
`y0` : | The new y coordinate of upper-left corner of original bounding box.
`x1` : | The new x coordinate of upper-right corner of original bounding box.
`y1` : | The new y coordinate of upper-right corner of original bounding box.
`x2` : | The new x coordinate of lower-left corner of original bounding box.
`y2` : | The new y coordinate of lower-left corner of original bounding box.
`x3` : | The new x coordinate of lower-right corner of original bounding box.
`y3` : | The new y coordinate of lower-right corner of original bounding box.
Returns : | The newly mapped item.

Since GIMP 2.8

### gimp_item_transform_rotate_simple ()

    gint32              gimp_item_transform_rotate_simple   (gint32 item_ID,
                                                             GimpRotationType rotate_type,
                                                             gboolean auto_center,
                                                             gdouble center_x,
                                                             gdouble center_y);

Rotate the specified item about given coordinates through the specified angle.

This function rotates the specified item. If a selection exists and the item is a drawable, the portion of the drawable which lies under the selection is cut from the drawable and made into a floating selection which is then rotated by the specified amount. The return value is the ID of the rotated item. If there was no selection or the item is not a drawable, this will be equal to the item ID supplied as input. Otherwise, this will be the newly created and rotated drawable. This procedure is affected by the following context setters: `gimp_context_set_transform_resize()`.

`item_ID` : | The affected item.
`rotate_type` : | Type of rotation.
`auto_center` : | Whether to automatically rotate around the selection center.
`center_x` : | The hor. coordinate of the center of rotation.
`center_y` : | The vert. coordinate of the center of rotation.
Returns : | The rotated item.

Since GIMP 2.8

### gimp_item_transform_rotate ()

    gint32              gimp_item_transform_rotate          (gint32 item_ID,
                                                             gdouble angle,
                                                             gboolean auto_center,
                                                             gdouble center_x,
                                                             gdouble center_y);

Rotate the specified item about given coordinates through the specified angle.

This function rotates the specified item. If a selection exists and the item is a drawable, the portion of the drawable which lies under the selection is cut from the drawable and made into a floating selection which is then rotated by the specified amount. The return value is the ID of the rotated item. If there was no selection or the item is not a drawable, this will be equal to the item ID supplied as input. Otherwise, this will be the newly created and rotated drawable. This procedure is affected by the following context setters: `gimp_context_set_interpolation()`, `gimp_context_set_transform_direction()`, `gimp_context_set_transform_resize()`, `gimp_context_set_transform_recursion()`.

`item_ID` : | The affected item.
`angle` : | The angle of rotation (radians).
`auto_center` : | Whether to automatically rotate around the selection center.
`center_x` : | The hor. coordinate of the center of rotation.
`center_y` : | The vert. coordinate of the center of rotation.
Returns : | The rotated item.

Since GIMP 2.8

### gimp_item_transform_scale ()

    gint32              gimp_item_transform_scale           (gint32 item_ID,
                                                             gdouble x0,
                                                             gdouble y0,
                                                             gdouble x1,
                                                             gdouble y1);

Scale the specified item.

This procedure scales the specified item. If a selection exists and the item is a drawable, the portion of the drawable which lies under the selection is cut from the drawable and made into a floating selection which is then scaled by the specified amount. The return value is the ID of the scaled item. If there was no selection or the item is not a drawable, this will be equal to the item ID supplied as input. Otherwise, this will be the newly created and scaled drawable. This procedure is affected by the following context setters: `gimp_context_set_interpolation()`, `gimp_context_set_transform_direction()`, `gimp_context_set_transform_resize()`, `gimp_context_set_transform_recursion()`.

`item_ID` : | The affected item.
`x0` : | The new x coordinate of the upper-left corner of the scaled region.
`y0` : | The new y coordinate of the upper-left corner of the scaled region.
`x1` : | The new x coordinate of the lower-right corner of the scaled region.
`y1` : | The new y coordinate of the lower-right corner of the scaled region.
Returns : | The scaled item.

Since GIMP 2.8

### gimp_item_transform_shear ()

    gint32              gimp_item_transform_shear           (gint32 item_ID,
                                                             GimpOrientationType shear_type,
                                                             gdouble magnitude);

Shear the specified item about its center by the specified magnitude.

This procedure shears the specified item. If a selection exists and the item is a drawable, the portion of the drawable which lies under the selection is cut from the drawable and made into a floating selection which is then sheard by the specified amount. The return value is the ID of the sheard item. If there was no selection or the item is not a drawable, this will be equal to the item ID supplied as input. Otherwise, this will be the newly created and sheard drawable. The shear type parameter indicates whether the shear will be applied horizontally or vertically. The magnitude can be either positive or negative and indicates the extent (in pixels) to shear by. This procedure is affected by the following context setters: `gimp_context_set_interpolation()`, `gimp_context_set_transform_direction()`, `gimp_context_set_transform_resize()`, `gimp_context_set_transform_recursion()`.

`item_ID` : | The affected item.
`shear_type` : | Type of shear.
`magnitude` : | The magnitude of the shear.
Returns : | The sheared item.

Since GIMP 2.8

### gimp_item_transform_2d ()

    gint32              gimp_item_transform_2d              (gint32 item_ID,
                                                             gdouble source_x,
                                                             gdouble source_y,
                                                             gdouble scale_x,
                                                             gdouble scale_y,
                                                             gdouble angle,
                                                             gdouble dest_x,
                                                             gdouble dest_y);

Transform the specified item in 2d.

This procedure transforms the specified item. If a selection exists and the item is a drawable, the portion of the drawable which lies under the selection is cut from the drawable and made into a floating selection which is then transformed. The transformation is done by scaling the image by the x and y scale factors about the point (source_x, source_y), then rotating around the same point, then translating that point to the new position (dest_x, dest_y). The return value is the ID of the rotated drawable. If there was no selection or the item is not a drawable, this will be equal to the item ID supplied as input. Otherwise, this will be the newly created and transformed drawable. This procedure is affected by the following context setters: `gimp_context_set_interpolation()`, `gimp_context_set_transform_direction()`, `gimp_context_set_transform_resize()`, `gimp_context_set_transform_recursion()`.

`item_ID` : | The affected item.
`source_x` : | X coordinate of the transformation center.
`source_y` : | Y coordinate of the transformation center.
`scale_x` : | Amount to scale in x direction.
`scale_y` : | Amount to scale in y direction.
`angle` : | The angle of rotation (radians).
`dest_x` : | X coordinate of where the center goes.
`dest_y` : | Y coordinate of where the center goes.
Returns : | The transformed item.

Since GIMP 2.8

### gimp_item_transform_matrix ()

    gint32              gimp_item_transform_matrix          (gint32 item_ID,
                                                             gdouble coeff_0_0,
                                                             gdouble coeff_0_1,
                                                             gdouble coeff_0_2,
                                                             gdouble coeff_1_0,
                                                             gdouble coeff_1_1,
                                                             gdouble coeff_1_2,
                                                             gdouble coeff_2_0,
                                                             gdouble coeff_2_1,
                                                             gdouble coeff_2_2);

Transform the specified item in 2d.

This procedure transforms the specified item. If a selection exists and the item is a drawable, the portion of the drawable which lies under the selection is cut from the drawable and made into a floating selection which is then transformed. The transformation is done by assembling a 3x3 matrix from the coefficients passed. The return value is the ID of the transformed item. If there was no selection or the item is not a drawable, this will be equal to the item ID supplied as input. Otherwise, this will be the newly created and transformed drawable. This procedure is affected by the following context setters: `gimp_context_set_interpolation()`, `gimp_context_set_transform_direction()`, `gimp_context_set_transform_resize()`, `gimp_context_set_transform_recursion()`.

`item_ID` : | The affected item.
`coeff_0_0` : | coefficient (0,0) of the transformation matrix.
`coeff_0_1` : | coefficient (0,1) of the transformation matrix.
`coeff_0_2` : | coefficient (0,2) of the transformation matrix.
`coeff_1_0` : | coefficient (1,0) of the transformation matrix.
`coeff_1_1` : | coefficient (1,1) of the transformation matrix.
`coeff_1_2` : | coefficient (1,2) of the transformation matrix.
`coeff_2_0` : | coefficient (2,0) of the transformation matrix.
`coeff_2_1` : | coefficient (2,1) of the transformation matrix.
`coeff_2_2` : | coefficient (2,2) of the transformation matrix.
Returns : | The transformed item.

Since GIMP 2.8