Using Layers for Masking in Java

Encoder Code39 in Java Using Layers for Masking

A mask is a layer that you create specifically to let some areas of an image show while you keep other areas hidden Fireworks uses two kinds of masks bitmap masks and vector masks (you can use text as a vector

mask) Both kinds of masks have one thing in common what they do: When you lay a mask over an image, the mask blocks out parts of the image and lets other parts show through The shape of the mask determines which parts show through and which are blocked out, as Figure 5-4 shows you

When you use a bitmap mask, the grayscale values of the mask determine what, and how much, shows through The lighter the pixel, the more the object or objects beneath show through The darker the pixel, the less the stuff underneath shows through A vector mask, on the other hand, uses the shape outline of the vector object like a cookie cutter However, Fireworks gives you a lot more flexibility than you have with a real cookie cutter! For example, you can anti-alias (smooth out jagged edges) and even feather (blur) the edges of your mask, or you can change the size of your mask at any time after you ve created it Fireworks offers many ways to create masks We cover the basics here, but you can always refer to the Fireworks Help files if you want to explore masks more in-depth

To make a bitmap mask using an existing bitmap, follow these steps:

1 If you want to mask multiple objects, group them by selecting them and using the key command Ctrl+G 2 Select the object you want to use to make the mask You can select multiple objects to make a mask by Shift+clicking them, but if you do, Fireworks automatically makes a vector mask, not a bitmap mask See the section Creating a vector mask, later in this chapter, if you want to make a vector mask that uses multiple bitmap objects 3 Choose Edit Cut, or use the key command Ctrl+X Cut That s right You paste the shape in a couple of steps 4 Select the layer, object, or group you want to be visible through the mask by selecting it in the Layers panel or on the canvas The layer, object, or group is highlighted 5 Choose Edit Paste as Mask All the parts of the masked image that fall outside the masking object disappear In the Layers panel, the mask icon shows up in the third column, and a link icon and thumbnail of the mask shape show up next to the thumbnail of the masked image 6 If it s not already selected, select Alpha channel in the Property inspector When the mask is selected in the Layers panel, the Property inspector offers two options for a bitmap mask: Mask to Alpha Channel and Mask to Grayscale (the default), as Figure 5-5 shows you Mask to Alpha Channel uses the transparency of the mask bitmap, and Mask to Grayscale uses the brightness of the pixels in the mask bitmap You can think of bitmaps as having four channels: Red, Green, Blue, and Alpha The Red, Green, and Blue channels describe the amount of each of those colors in every pixel in the bitmap The Alpha channel contains information about the level of transparency of each pixel in the bitmap

You can hide a mask temporarily by clicking it in the Layers panel and then choosing Disable Mask from the Layers panel s Options menu (the bulleted list icon at the top right of the panel) The mask icon disappears from the Show/Hide object column and a red X appears over the mask, indicating that the mask is disabled To re-enable the mask, simply click it To make a bitmap mask by creating an empty mask and modifying it, follow these steps: 1 Select the object you want to mask by clicking it on the canvas or in the Layers panel 2 Click the Mask button at the bottom of the Layers panel or choose Modify Mask Reveal All The Mask icon is the rectangle with a dotted circle inside Reveal All means the mask you made is completely transparent until you modify it 3 Select a paintbrush or other drawing tool and draw on top of the bitmap Wherever you draw, the mask blocks the image behind What if you want to do the opposite, reveal what s underneath only where you draw Easy! Just follow these steps: 1 Select the object you want to mask by clicking it on the canvas or in the Layers panel 2 Choose Modify Mask Hide All Hide All means the mask you made is completely opaque until you modify it, so when you first apply the mask, it looks like your masked object has disappeared 3 Select any color other than black Because the opaque areas of the mask appear black, you have to draw the areas that you want to show through by using any other color 4 Select a paintbrush or other drawing tool and draw on top of the bitmap Wherever you draw, the mask reveals the image behind You can delete a mask by clicking it in the Layers panel and then choosing Delete Mask from the Layers panel s Options menu (the bulleted list icon at the top right of the panel) When you delete a mask, a dialog box appears to give you the option to apply the mask before deleting it, which changes the masked image