Category: Android paint shader example

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Skip to content. Permalink Dismiss Join GitHub today GitHub is home to over 40 million developers working together to host and review code, manage projects, and build software together. Sign up. Branch: master. Find file Copy path. No definitions found in this file. Cannot retrieve contributors at this time. Raw Blame History. Context ; import android. Bitmap ; import android. BitmapFactory ; import android. BitmapShader ; import android.

Canvas ; import android. Color ; import android. Paint ; import android. Path ; import android. PorterDuff ; import android. PorterDuffXfermode ; import android. Shader ; import android. AttributeSet ; import android.The most important part of a custom view is its appearance. Custom drawing can be easy or complex according to your application's needs. This lesson covers some of the most common operations. Beyond this lesson, you can find additional related information at Canvas and Drawables.

The most important step in drawing a custom view is to override the onDraw method. The parameter to onDraw is a Canvas object that the view can use to draw itself. The Canvas class defines methods for drawing text, lines, bitmaps, and many other graphics primitives. You can use these methods in onDraw to create your custom user interface UI. Before you can call any drawing methods, though, it's necessary to create a Paint object.

The next section discusses Paint in more detail. The android. For instance, Canvas provides a method to draw a line, while Paint provides methods to define that line's color.

Canvas has a method to draw a rectangle, while Paint defines whether to fill that rectangle with a color or leave it empty. Simply put, Canvas defines shapes that you can draw on the screen, while Paint defines the color, style, font, and so forth of each shape you draw. So, before you draw anything, you need to create one or more Paint objects.

The PieChart example does this in a method called initwhich is called from the constructor from Java, but we can initialise inline in Kotlin:. Creating objects ahead of time is an important optimization. Views are redrawn very frequently, and many drawing objects require expensive initialization. Creating drawing objects within your onDraw method significantly reduces performance and can make your UI appear sluggish.

In order to properly draw your custom view, you need to know what size it is. Complex custom views often need to perform multiple layout calculations depending on the size and shape of their area on screen. You should never make assumptions about the size of your view on the screen. Even if only one app uses your view, that app needs to handle different screen sizes, multiple screen densities, and various aspect ratios in both portrait and landscape mode.

Although View has many methods for handling measurement, most of them do not need to be overridden. If your view doesn't need special control over its size, you only need to override one method: onSizeChanged.

Calculate positions, dimensions, and any other values related to your view's size in onSizeChangedinstead of recalculating them every time you draw. In the PieChart example, onSizeChanged is where the PieChart view calculates the bounding rectangle of the pie chart and the relative position of the text label and other visual elements. When your view is assigned a size, the layout manager assumes that the size includes all of the view's padding.

You must handle the padding values when you calculate your view's size. Here's a snippet from PieChart. If you need finer control over your view's layout parameters, implement onMeasure. This method's parameters are View. MeasureSpec values that tell you how big your view's parent wants your view to be, and whether that size is a hard maximum or just a suggestion.

As an optimization, these values are stored as packed integers, and you use the static methods of View. MeasureSpec to unpack the information stored in each integer. Here's an example implementation of onMeasure.

In this implementation, PieChart attempts to make its area big enough to make the pie as big as its label:.A Drawable resource is a general concept for a graphic which can be drawn.

The simplest case is a graphical file bitmapwhich would be represented in Android via a BitmapDrawable class.

The ADT project creation wizard creates these folders by default. If these bitmaps are provided in different folder, the Android system selects the correct one automatically based on the device configuration. If you do not provide bitmaps for all supported resolutions, the Android system scales the closest fit up or down.

This is typically undesired as the bitmap might get blury. In addition to graphical files, Android supports XML drawables and 9-patch graphics. XML drawables are used to describe shapes color, border, gradientstate, transitions and more. Drawables can also be written in Java code. Every object which implements Drawable can be used as a Drawable in code. In code you can also assign drawables to views. Most views accept an resource ID as input parameter. For example the following code shows how to set a drawables as background to an ImageView.

Android allows you to use the Bitmap class for working with bitmaps.

Android Lesson Four: Introducing Basic Texturing

This section explain how to create Bitmap objects via Java code and how to convert Bitmap into Drawable objects and vice versa. If required you can load any accessible bitmap file in your code and convert them into Drawables objects.

The following example code shows how to create an Bitmap object for the assets folder and assign it to an ImageView. The following code demonstrates that.

To convert a Bitmap object into a Drawable you can use the following code. Shape Drawables are XML files which allow to define a geometric object with colors, borders and gradients which can get assigned to Views. State drawables allow to define states. For each state a different drawable can get assigned to the View. For example the following defines different drawables for a button depending on its state.

As of API level 21 you can use vector drawables in your Android application.

android paint shader example

These are similar to svg files but with a limited scope. Using vector drawables automatically scale to the density of the device. The following listing demonstrates its usage in the vectordrawable. Android also support animated vector drawables via the AnimatedVectorDrawable class.

It allows to combine vector drawables with animations. With vector drawables you can create different images and morph between them and can start and stop it via your code. You cannot control the animation nor pause the animation at a particular frame.This codelab is part of the Advanced Android in Kotlin course.

You'll get the most value out of this course if you work through the codelabs in sequence, but it is not mandatory. All the course codelabs are listed on the Advanced Android in Kotlin codelabs landing page.

In computer graphics, a shader is a type of computer program that was originally used for shading the production of appropriate levels of light, darkness, and color within an imagebut which now performs a variety of specialized functions in various fields of computer graphics special effects. In Android, Shader defines the color s or the texture with which the Paint object should draw other than a bitmap.

For example, you can use a BitmapShader to define a bitmap as a texture to the Paint object. This allows you to implement custom themes with translucent effects, and custom views with a bitmap as a texture. You can also use masks with transition animations to create impressive visual effects.

To draw images in different shapes rounded rectangle in this exampleyou can define a BitmapShader for your Paint object and use the drawRoundRect method to draw a rectangle with rounded corners, as shown below.

In this codelab, you will use a BitmapShader to set a bitmap as a texture to the Paint object, instead of a simple color. The FindMe app lets you search for an Android image on a dark phone screen using a "spotlight. The following screenshots show the FindMe app at startup, when the user is dragging their finger, and after the user has found the Android image by moving around the spotlight.

In this task, you create the FindMe app from scratch, so you will set up a project and define some strings. This class is where game play takes place. After Android Studio adds the constructor from the AppCompatImageView class, the generated code should look like the code below. A Shader defines the texture for a Paint object.

A subclass of Shader is installed in a Paint by calling paint. After that, any object other than a bitmap that is drawn with that Paint will get its color s from the shader. The PorterDuff. Mode class provides several Alpha compositing and blending modes. Alpha compositing is the process of compositing or combining a source image with a destination image to create the appearance of partial or full transparency. Transparency is defined by the alpha channel. The alpha channel represents the degree of transparency of a color, that is, for its red, green and blue channels.

To learn about blending modes, see the blending modes documentation. The destination pixels that cover source pixels, are kept, and the remaining source and destination pixels are discarded.

To learn more about the other modes, refer to the Alpha compositing modes documentation. The tiling mode, TileModedefined in the Shaderspecifies how the bitmap drawable is repeated or mirrored in the X and Y directions if the bitmap drawable being used for texture is smaller than the screen.Recently i wanted to create a glowing version of a dot, to indicate the active state.

Really its just to get the effect of a glowing LED.

Android example source code file (ComposeShader.java)

As you can see its a symbolic representation. So i created it using a Paint that contains a Shader which is made from a RadialGradient. In this example, the center of the gradient is the same as the center of the circle, and one color is used twice in the gradient. The radius of the glowing dot is nearly twice that of the plain circles. This code is used within an activity that contains a view class with onDraw.

The canvas. It is easily adapted to draw onto a canvas that then is used to fill a bitmap. In this example, i have set the center of the gradient to the center of the drawn circle, and the radius of the gradient is the same as the circle. The gradient will end at the edge of the drawn circle. CLAMP. Like Like. Do you have any idea how to set pixel color a gradient color with floodfill or with any other method?

You are commenting using your WordPress. You are commenting using your Google account. You are commenting using your Twitter account.

You are commenting using your Facebook account. Notify me of new comments via email. Notify me of new posts via email. Skip to content Recently i wanted to create a glowing version of a dot, to indicate the active state. Here is how to do it, with the following reservations: the gradient may appear very banded, not smooth — especially when it is one color.

This is not necessarily due to the gradient itself, but the way it is expressed onto the screen by the device. The above image is from a device screenshot, but on the actual device, it didnt look so smooth. In the above picture, the background color was used as the final color in the gradient. Important: Radial gradients have their own center. You can have the center of the gradient anywhere on — or off — the canvas. In this example the center of the gradient is in the center of the shape, to create a glowing button effect.This is the fourth tutorial in our Android series.

Each lesson in this series builds on the lesson before it. Here are the previous lessons in the series:. The art of texture mapping along with lighting is one of the most important parts of building up a realistic-looking 3D world.

Without texture mapping, everything is smoothly shaded and looks quite artificial, like an old console game from the 90s. The first games to start heavily using textures, such as Doom and Duke Nukem 3D, were able to greatly enhance the realism of the gameplay through the added visual impact — these were games that could start to truly scare us if played at night in the dark.

Shape Drawing Example In Android

Per fragment lighting; centered between four vertices of a square. Adding texturing; centered between four vertices of a square. In the image on the left, the scene is lit with per-pixel lighting and colored. Otherwise the scene appears very smooth. There are not many places in real-life where we would walk into a room full of smooth-shaded objects like this cube.

In the image on the right, the same scene has now also been textured. The ambient lighting has also been increased because the use of textures darkens the overall scene, so this was done so you could also see the effects of texturing on the side cubes.

The cubes have the same number of polygons as before, but they appear a lot more detailed with the new texture. For those who are curious, the texture source is from public domain textures. Texture coordinates In OpenGL, texture coordinates are sometimes referred to in coordinates s, t instead of x, y.

Another thing to note is that these texture coordinates are like other OpenGL coordinates: The t or y axis is pointing upwards, so that values get higher the higher you go. In most computer images, the y axis is pointing downwards. OpenGL ES also offers other texture modes that let you do different and more specialized effects. Here are the new changes:. In the vertex shader, we add a new attribute of type vec2 an array with two components that will take in texture coordinate information as input.

This will be per-vertex, like the position, color, and normal data. We also add a new varying that will pass this data through to the fragment shader via linear interpolation across the surface of the triangle.

android paint shader example

We add a new uniform of type sampler2D to represent the actual texture data as opposed to texture coordinates. We then take this value and multiply it with the other terms to get the final output color. Adding in a texture this way darkens the overall scene somewhat, so we also boost up the ambient lighting a bit and reduce the lighting attenuation. This bit of code will read in a graphics file from your Android res folder and load it into OpenGL. We first need to ask OpenGL to create a new handle for us.

This handle serves as a unique identifier, and we use it whenever we want to refer to the same texture in OpenGL.So, Hello World!

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Hope you are learning well. In this blog, we will learn TextView decoration in Android. This blog is going to be an interesting blog as we all use TextViews in our Android application to display some textual information. In this blog, we will learn how to decorate these TextViews in Android.

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In the beginning, we will learn some of the basic attributes of TextView and after that, we will be having some cool TextViews in our app. A TextView is a user interface element that is used to display some text or some textual information in our application.

By using the TextView tag in your application, you can insert a TextView to display the desired text by using android:text property.

To decorate a TextView, there are various attributes that can be used. By default, Android gives you four fonts that you can use in your application. They are:. You can use these fonts in your TextView by using the android:typeface attribute. You can emphasize a text by using the android:textStyle attribute. Following are the three options that are available with android:textStyle :. You can change the text size by using the android:textSize attribute and the color of the text can be change by using android:textColor attribute.

You can change the font family of a TextView by using the android:fontFamily attribute.

android paint shader example

By default, we have 14 font families that can be used in TextView. Some of these are serif, monospace, casual, cursive, sans-serif, sans-monospace, etc. ImageIf you want to use your custom font then you can read our blog at MindOrks Blogs.

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You can align your text with the help of android:textAlignment attribute. This attribute provides us a lot of options like center align, textStart, textEnd, viewStart, viewEnd, etc. You can put shadow to your text and change the color of the shadow by using the android:shadowColor attribute. Also, you can use shadowDx and shadowDy to specify the offset of the shadow. You can put a sentence in more than one line. This is possible when the width of the TextView is not enough to hold the contents of the TextView i.

Also, add the below code in you MainActivity. While reading a text, you can go to somewhere else by clicking on the text. This is the same way as used in websites, where we use hyperlinks to open new page from the existing one.

Add the below code in your XML file:. Here, textColorLink is the color of the clickable link and the textColorHighlight is the color used when you click the link. Add the below code in your MainActivity. You can use some background image in TextView i.

After that, add the below code in your MainActivity. In this blog, we learned how we can decorate TextViews in our application. We learned many ways of decorating the text used in our application. Hope you enjoyed this blog and will implement the learnings of this blog in your application.

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android paint shader example

Android TextView Decoration Tutorial. Share this blog to spread the knowledge.


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