3. Deshacer
| Capítulo 3. Primeros pasos con Wilber |

## 3. Deshacer

Almost anything you do to an image in GIMP can be undone. You can undo the most recent action by choosing Edit → Undo from the image menu, but this is done so frequently that you really should memorize the keyboard shortcut, Ctrl+Z.

El deshacer puede a su vez deshacerse. Luego de haber deshecho una acción, puede rehacerla escogiendo Editar → Rehacer del el menú de la imagen, o usando el atajo de teclado, Ctrl+Y. A menudo es útil juzgar el efecto de una acción deshaciéndola y rehaciéndola repetidamente. Esto usualmente se realiza muy rápido, y no consume recursos extra, ni altera el historial de deshacer. Así que no se produce daño al hacer esto.

| Atención
If you undo one or more actions and then operate on the image in any way except by using Undo or Redo, it will no longer be possible to redo those actions: they are lost forever. The solution to this, if it creates a problem for you, is to duplicate the image and then test on the copy. ( Do Not test the original, because the undo/redo history is not copied when you duplicate an image.)

Si a menudo se encuentras deshaciendo y rehaciento muchos pasos a la vez, puede ser más conveniente trabajar con el Historial de deshacer. Éste es un diálogo empotrable que muestra una pequeña imagen para cada punto del historial de acciones, y permite retroceder o avanzar hacia cierto punto efectuando clics.

Undo is performed on an image-specific basis: the "Undo History" is one of the components of an image. GIMP allocates a certain amount of memory to each image for this purpose. You can customize your Preferences to increase or decrease the amount, using the Environment page of the Preferences dialog. There are two important variables: the minimal number of undo levels, which GIMP will maintain regardless of how much memory they consume, and the maximum undo memory, beyond which GIMP will begin to delete the oldest items from the Undo History.

| Nota
Even though the Undo History is a component of an image, it is not saved when you save the image using GIMP's native XCF format, which preserves every other image property. When the image is reopened, it will have an empty Undo History.

GIMP's implementation of Undo is rather sophisticated. Many operations require very little Undo memory (e.g., changing visibility of a layer), so you can perform long sequences of them before they drop out of the Undo History. Some operations, such as changing layer visibility, are compressed, so that doing them several times in a row produces only a single point in the Undo History. However, there are other operations that may consume a lot of undo memory. Most filters are implemented by plug-ins, so the GIMP core has no efficient way of knowing what changed. As such, there is no way to implement Undo except by memorizing the entire contents of the affected layer before and after the operation. You might only be able to perform a few such operations before they drop out of the Undo History.

### 3.1. Las acciones que no se pueden deshacer

Most actions that alter an image can be undone. Actions that do not alter the image generally cannot be undone. Examples include saving the image to a file, duplicating the image, copying part of the image to the clipboard, etc. It also includes most actions that affect the image display without altering the underlying image data. The most important example is zooming. There are, however, exceptions: toggling QuickMask on or off can be undone, even though it does not alter the image data.

Hay unas pocas acciones importantes que alteran una imagen pero no pueden deshacerse:

La clausura de la imagen

  The Undo History is a component of the image, so when the image is closed and all of its resources are freed, the Undo History is gone. Because of this, unless the image has not been modified since the last time it was saved, GIMP always asks you to confirm that you really want to close the image. (You can disable this in the Environment page of the Preferences dialog; if you do, you are assuming responsibility for thinking about what you are doing.)

Revertir la imagen

  “Reverting” means reloading the image from the file. GIMP actually implements this by closing the image and creating a new image, so the Undo History is lost as a consequence. Because of this, if the image is unclean, GIMP asks you to confirm that you really want to revert the image.

“Porciones” de acciones

  Algunas herramientas requieren que realice una compleja serie de manipulaciones antes de que surtan efecto, pero sólo permiten deshacerse en su totalidad en lugar de hacerlo para sus elementos individuales. Por ejemplo, las tijeras inteligentes requieren que Ud. cree un camino cerrado efectuando clics en múltiples puntos de la imagen, y que luego haga clic dentro del camino para crear una selección. No puede deshacer los clics individualmente: si deshace luego de haber terminado, se vuelve al punto inicial. Para dar otro ejemplo, cuando trabaja con la herramienta de texto, no puede deshacer cada letra individualmente, ni los cambios de tipografía, etc. Si deshace luego de haber terminado, se borra la capa de texto creada.

Filters, and other actions performed by plugins or scripts, can be undone just like actions implemented by the GIMP core, but this requires them to make correct use of GIMP's Undo functions. If the code is not correct, a plugin can potentially corrupt the Undo History, so that not only the plugin but also previous actions can no longer properly be undone. The plugins and scripts distributed with GIMP are all believed to be set up correctly, but obviously no guarantees can be given for plugins you obtain from other sources. Also, even if the code is correct, canceling a plugin while it is running may corrupt the Undo History, so it is best to avoid this unless you have accidentally done something whose consequences are going to be very harmful.

2.3. Diálogos empotrables |  | 4. GIMP-Soluciones rápidas