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The Options Menu
2:39In this video we'll learn about what an Options Menu is, and we'll take a look at the app we'll be creating!
[MUSIC]
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Hey there.
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I'm Ben, and in this workshop we're going
to learn how to use the options menu.
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The options menu is the set of options you
usually see at the top of an application,
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and it's where you should place any
actions related to the current activity.
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Let's take a look at the app we'll
be making to get acquainted with
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the options menu.
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In this workshop we'll be making
an app to let us change the colors
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of a few preloaded images.
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Up here is the options menu, where we
have two items being displayed, and
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four more in the overflow menu.
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The first item lets us cycle
through the three images.
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And the second one toggles the image
between color, and black and white.
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In the overflow menu we have
a check box for each color channel.
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And if we uncheck one,
that color is removed from the image.
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Finally, the Reset button just
resets the image to normal.
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And one more thing, if we have a black and
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white image, it doesn't really make
sense to remove color from it.
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So we're not going to show
the color options unless it's
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actually a color image.
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That's enough about the project for
now, let's start making it.
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If you'd like to follow along,
pause me and
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download the starter project
from the teacher's notes below.
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All right, now that we've got our project,
let's open up MainActivity and
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see what we're working with.
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At the top we've got a few fields.
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There's one for our imageView, followed by
an array to store our resource IDs, and
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an imageIndex to store which
resource ID we're using.
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Then there's a boolean variable to
determine if the image is in color.
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And finally three more booleans
to determine whether each color
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should be on or off.
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In the onCreate method,
we just set our layout,
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populate the imageView field, and
then call the loadImage method.
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If you try to load a large
image into an imageView,
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Android will throw an out of memory error.
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However, by using the Glide library,
we don't have to worry about that, and
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we can just load the image
right into the imageView.
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At the bottom of the class, we have two
more functions that aren't being used yet.
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The first is updateSaturation, which
will toggle the image between color, and
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black and white,
depending on the value of our color field.
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The second method is updateColors.
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This method will set the colors of our
image based on the values of the red,
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green, and blue fields.
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All right,
that should be enough to get us started.
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In the next video we'll start
implementing our options menu.
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