Creating Instruction Guide using Bottomsheet

The PSLab android app consists of different instruments like oscilloscope, multimeter, wave generator etc and each instrument has different functionality and usage so it is necessary that there should be an instruction guide for every instrument so that the user can easily read the instruction to understand the functionality of the instrument.

In this we will create an instruction guide for the Wave Generator which will contain information about the instrument, it’s functionalities, steps for how to use the instrument.

The main component that I used to create instruction guide is Bottom SheetBottom Sheet is introduced in Android Support v23.2 . It is a special UI widget which slide up from the bottom of the screen and it can be used to reveal some extra information that we cannot show on the main layout like bottom menus,  instructions etc.

They are of two types :

  1. Modal Bottom Sheet:–  This Bottom Sheet has properties very similar to normal dialogs present in Android like elevation only difference is that they pop up from the bottom of screen with proper animation and they are implemented using BottomSheetDialogFragment Class.

  2. Persistent Bottom Sheet:– This Bottom Sheet is included as a part of the layout and they can be slid up and down to reveal extra information. They are implemented using BottomSheetBehaviour Class.

For my project, I used persistent Bottom Sheet as modal Bottom Sheet can’t be slid up and down by the swipe of the finger whereas persistent Bottom Sheet can be slid up and down and can be hidden by swipe features.

Implementing the Bottom Sheet

Step 1: Adding the Dependency

To start using Bottom Sheet we have to add the dependency (We have also include Jake Wharton-Butterknife library for view binding but it is optional.)

dependencies {

   implementation fileTree(include: ['*.jar'], dir: 'libs')

   implementation "com.android.support:appcompat-v7:26.0.1"
   implementation "com.android.support:design:26.0.1"
   implementation "com.jakewharton:butterknife:8.8.1"

   annotationProcessor "com.jakewharton:butterknife-compiler:8.8.1"

Step 2: Creating Bottom Sheet layout file

In this step, we will create the layout of the Bottom Sheet, as our purpose of making Bottom Sheet is to show extra information regarding the instrument so we will include ImageView and TextView inside the layout that will be used to show the content later.

Some attributes in the layout worth noting are:

  • app:layout_behavior: This attribute makes the layout act as Bottom Sheet.
  • app:behavior_peekHeight: This is the height of the Bottom Sheet when it is minimized.
  • app:behavior_hideable: Defines if the Bottom Sheet can be hidden by swiping it down.

Here, we will also create one extra LinearLayout having height equal to the peek_height. This  LinearLayout will be at the top of the BottomSheet as shown in Figure 1 and it will be visible when the BottomSheet is in a minimized state(not hidden). Here we will put text view with like “Show guide” and an arrow pointing upwards so that it is easier for the user to understand that sheet can be viewed by sliding up.

Figure 1 LinearLayout containing textview and imageview

Here is the gist[2] that contains code for the layout of the Bottom Sheet guide

After this step, we can see a layout of Bottom Sheet in our Android Editor as shown in Figure 2

Figure 2 shows the layout of the Bottom Sheet

Step 3: Creating the Container view layout containing content and Bottom Sheet

For container view, we will create new layout under Res Layout and name it “container_view_wavegenerator.xml”

In this layout, we will use ‘Coordinator Layout’ as ViewGroup because persistent Bottom Sheet is implemented using BottomSheetBehavior class which can only be applied to the child of ‘CoordinatorLayout’.

Then add the main layout of our instrument and the layout of the Bottom Sheet inside this layout as its child.

<android.support.design.widget.CoordinatorLayout xmlns:android="http://schemas.android.com/apk/res/android"
   android:layout_width="match_parent"
   android:layout_height="match_parent">

   <include layout="@layout/activity_wave_generator" />

   <include layout="@layout/bottom_sheet_custom" />

Step 4: Setting Up Bottom Sheet and Handling callbacks

Now we will head over to the “WaveGenerator.java” file(or any instrument java file)Here we will handle set up Bottom Sheet and handle callbacks by using following classes:

BottomSheetBehavior provides callbacks and makes the Bottom Sheet work with CoordinatorLayout.

BottomSheetBehavior.BottomSheetCallback() provides the callback when the Bottom Sheet changes its state. It has two methods that need to be overridden:

  1. public void onSlide(@NonNull View bottomSheet, float slideOffset)

    This method is called when the Bottom Sheet slides up and down on the screen. It has slideOffset as a parameter whose value varies from -1.0 to 0.0 when the Bottom Sheet comes from the hidden state to collapsed and 0.0 to 1.0 when it goes from collapsed state to expanded state.

  2. public void onStateChanged(@NonNull View bottomSheet, int newState)

    This method is called when BottomSheet changed its state. Here, let us also understand the different states which can be attained by the Bottom Sheet:

    • BottomSheetBehavior.STATE_EXPANDED : When the Bottom Sheet is fully expanded showing all the content.
    • BottomSheetBehavior.STATE_HIDDEN : When the Bottom Sheet is hidden at the bottom of the layout.
    • BottomSheetBehavior.STATE_COLLAPSED : When the Bottom Sheet is in a collapsed state that is only the peek_height view part of the layout is visible.
    • BottomSheetBehavior.STATE_DRAGGING : When the Bottom Sheet is dragging.
    • BottomSheetBehavior.STATE_SETTLING : When the Bottom Sheet is settling either at expanded height or at collapsed height.

We will implement these methods in our instrument class, and also put the content that needs to be put inside the Bottom Sheet.

@BindView(R.id.bottom_sheet)
LinearLayout bottomsheet;
@BindView(R.id.guide_title)
TextView bottomSheetGuideTitle;
@BindView(R.id.custom_dialog_schematic)
ImageView bottomSheetSchematic;
@BindView(R.id.custom_dialog_desc)
TextView bottomSheetDesc;

BottomSheetBehavior bottomSheetBehavior;

@Override
protected void onCreate(Bundle savedInstanceState) { 
              
           //main instrument implementation code

           setUpBottomSheet()
}

private void setUpBottomSheet() {

   bottomSheetBehavior = BottomSheetBehavior.from(bottomsheet);

    bottomSheetGuideTitle.setText(R.string.wave_generator);
   bottomSheetSchematic.setImageResource(R.drawable.sin_wave_guide);
   bottomSheetDesc.setText(R.string.wave_gen_guide_desc);

  bottomSheetBehavior.setBottomSheetCallback(new 
  BottomSheetBehavior.BottomSheetCallback() {
       @Override
       public void onStateChanged(@NonNull View bottomSheet, int newState) {
           if (newState == BottomSheetBehavior.STATE_EXPANDED) {
               bottomSheetSlideText.setText(R.string.hide_guide_text);
           } else {
               bottomSheetSlideText.setText(R.string.show_guide_text);
           }
       }

       @Override
       public void onSlide(@NonNull View bottomSheet, float slideOffset) {
           Log.w("SlideOffset", String.valueOf(slideOffset));
        }
      });
}

After following all the above steps the Bottom Sheet will start working properly in the Instrument layout as shown in Figure 3

Figure 3 shows the Bottom Sheet in two different states

To read more about implementing Bottom Sheet in layout refer this: AndroidHive article- working with bottomsheet

Resources

  1. Developer Documentation – BottomSheetBehaviour
  2. Gist containing xml file for layout of Custom Bottomsheet

Continue Reading Creating Instruction Guide using Bottomsheet

Creating Control Panel For Wave Generator using Constraint Layout

 

In the blog Creating the onScreen Monitor Using CardView I had created the monitors to view the wave properties in this blog we will create the UI of controlling panel that will be used for that monitors with multiple buttons for both analog and digital waveforms.

Which layout to choose?

In today’s world, there are millions of Android devices present with different screen sizes and densities and the major concern of an Android developer is to make the layout that fits all the devices and this task is really difficult to handle with a linear or relative layout with fixed dimensions.

To create a complex layout with lots of views inside the parent using linear layout we have to make use of the attribute layout_weight for their proper stretching and positioning, but such a complex layout require a lot of nesting of weights and  android tries to avoid it by giving a warning :

Nested Weights are bad for performance

This is because layout_weight attribute requires a widget to be measured twice[1]. When a LinearLayout with non-zero weights is nested inside another LinearLayout with non-zero weights, then the number of measurements increases exponentially.

So, to overcome this issue we will make use of special type of layout “Constraint Layout” which was introduced in Google I/O 2016.

Features of Constraint Layout:-

  • It is similar to Relative Layout as all views are laid out according to their relationship with the sibling, but it is more flexible than Relative Layout.
  • It helps to flatten the view hierarchy for complex layouts.
  • This layout is created with the help of powerful tool provided by Android which has a palette on the left-hand side from where we can drag and drop the different widgets like TextView, ImageView, Buttons etc. and on the right-hand side it provides options for positioning, setting margins and other styling option like setting color, change text style etc.
  • It automatically adjusts the layout according to the screen size and hence doesn’t require the use of layout_weight attribute.

In following steps, I will create the controlling panel for Wave generator which is a complex layout with lots of buttons with the help of constraint layout.

Step 1: Add the dependency of the Constraint Layout in the Project

To use Constraint layout add the following to your build.gradle file and sync the project

dependencies {
    implementation "com.android.support.constraint:constraint-layout:1.1.0"
}

Step 2: Applying Guidelines to the layout

Guidelines[3] are anchors that won’t be displayed in your app, they are like one line of a grid above your layout and can be used to attach or constraint your widgets to it. They are only visible on your blueprint or preview editor. These will help to position and constraint the UI components on the screen easily.

For adding guidelines :

As shown in Figure 1 Right-click anywhere on the layout -> Select helpers -> Select horizontal or vertical guideline according to your need.

Figure 1 shows the horizontal guideline being added to the layout.

And for positioning the guideline we have to set the value of attribute layout_constraintGuide_percent  

Let’s say we want the guideline to be at the middle of the screen so we’ll set :

app:layout_constraintGuide_percent=”0.50″

For my layout I have added three guideline :

  • One horizontal guideline at 50%
  • Two vertical guidelines at 30% and 65%

Doing this will bifurcate the screen into six square blocks as shown in below figure :

Figure 2 shows the blueprint of constraint layout containing two vertical and one horizontal guidelines with their percentage offset from respective bases

Step 3: Adding the buttons in the blocks

Until now we have created six squares blocks, now we have to put a button view in each of the boxes.

  • First drag and drop button view from the Palette (shown in Figure 3) on the left side inside the box.

    Figure 3 shows the layout editor palette

     

  • Then we have to set constraints of this button by clicking on the small circle present on the middle of edges and dragging it onto the side of the block facing it.

    Figure 4 shows the button widget getting constrained to sides

     

  • Set the layout_width and layout_height attribute of the button to be “0dp”, doing this the button will expand in all the direction occupying all the space with respect to the border it has been constrained with.

    Figure 6 shows the button widget expanding to all the available space in the box

Similarly, adding buttons in all the square blocks and providing proper theme color we will have a blueprint and layout as shown in Figure 6.

Figure 6 shows the waveform panel blueprint and actual layout for analog waves with six buttons

Following the same steps until now, I have created the other controlling panel layout having buttons for digital waves as shown in Figure 7

Figure 7 shows other constraint layout for digital waves having seven buttons

Detailing and combining the panels to form Complete UI

After adding both the panels we have created in this layout inside the Wave Generator we have the layout as shown in Figure 8

Figure 8 shows the UI of Wave Generator as shown by a actual Android device in the PSLab app.

As we can see on adding the panels the button created inside the layout shrink so as to adapt to the screen and giving out a beautiful button-like appearance.

Resources   

  1. Blog on Nested Weights are bad for performance
  2. Developer Article – Build a Responsive UI with ConstraintLayout
  3. Information about Guidelines

Continue Reading Creating Control Panel For Wave Generator using Constraint Layout

Making Shapes with PSLab Oscilloscope

Looking back to history, the first ever video game was ‘Pong’ which was played on an analog oscilloscope with a very small screen. Oscilloscopes are not made to play video games, but by just tinkering around its basic functionality which is display waveforms, we can do plenty of cool things. PSLab device also has an oscilloscope; in fact it’s a four channel oscilloscope.

This blog post will show you how the oscilloscope in PSLab is not just a cheap oscilloscope but it has lots of functionalities an industry grade oscilloscope has (except for the bandwidth limitation to a maximum of 2 MHz)

To produce shapes like above figures, we are using another instrument available in PSLab. That is ‘Waveform Generator’. PSLab Waveform Generator can generate three different waveforms namely Sine waves, Triangular waves and Square waves ranging from 5 Hz to 5 kHz.

To get started, first connect two jumper wires between SI1-CH1 and SI2-CH2 pins. We needn’t worry about ground pins as they are already internally connected. Now it’s time to open up the PSLab oscilloscope. Here we are going to utilize two channels for this activity and they will be CH1 and CH2. Check the tick boxes in front of ‘Chan 1’ and ‘Chan 2’ and set ‘Range’ to “+/-4V” to have the maximum visibility filling the whole screen with the waveform.

The shapes are drawn using a special mode called ‘X-Y Mode’ in PSLab oscilloscope. In this mode, two channels will be plotted against their amplitudes at every point in time.

As it is already mentioned that PSLab can generate many waveform types and also they can have different phase angles relative to each other. They can have different independent frequencies. With all these combinations, we can tweak the settings in Waveform Generator to produce different cool shapes in PSLab oscilloscope.

These shapes can vary from basic geometric shapes such as circle, square, rectangle to complicated shapes such as rhombus, ellipse and polynomial curves.

Circle

A circular shape can be made by generating two sine waves having the same frequency but with a phase difference of 90 degrees or 270 degrees between the two wave forms.

 

 
 

 


Square

Square shape can be made by generating two triangular waveforms again having the same frequency but with a phase difference of either 90 degrees or 270 degrees between the two.

 

 

 
 


Rectangle

Similar to creating a Square, by having the same frequency for both triangular waveforms but a different phase angle greater than or less than 90 degree will do the trick.

 

 

 
 


Rhombus

Keeping the waveform settings same for the rectangle, by changing the amplitude of the SI1 waveform using the knob we can generate a rhombic shape on the XY graph plot.

 

 

 
 


Ellipse

Generating ellipse is also similar to creating a rhombus. But here we are using sine waves instead of triangular waves. By changing the amplitude of SI1 using the knob we can change the curvature.

 

 

 


Helix

Helix or spiral shape can be generated using two sine waves having same phase but two different frequencies. Frequencies better be integer multiples of the smaller frequency to  have a steady shape.

 

 

 


Parabola

Parabolic shapes can be generated by mixing up triangular waves with sine waves with different phase angles.

 

 

 

 
 

More random shapes


References:

https://www.aps.org/publications/apsnews/200810/physicshistory.cfm

Continue Reading Making Shapes with PSLab Oscilloscope